refactor(de-sidecar): purge the "sidecar" name from live code, tests, and current docs

Completes the de-sidecar cleanup: no live code, test, current doc,
script, or nix file mentions or is named "sidecar" any more. Only the
dated PRD/research docs keep the term as historical record (agreed on
the #385 thread).

- Rename `sidecar_init.py`→`gateway_init.py` was done earlier; this pass
  sweeps the remaining descriptive uses: the egress / git-gate / supervise
  components are the gateway's *daemons*, the shared container is the
  *gateway*, the old per-bottle container was the *companion container*.
- Rename `tests/integration/test_sidecar_bundle_image.py`→`test_gateway_image.py`
  and its class; update `docs/ci.md` + `tests/README.md` for the renamed/
  removed integration tests.
- `SIDECAR_PORTS` shell var in `scripts/firecracker-netpool.sh`→`GATEWAY_PORTS`.

Full unit suite green (bar the pre-existing `/bin/sleep`-missing env
errors in test_gateway_init); docker integration — gateway singleton,
broker, real two-bottle multitenant isolation, and the gateway-image
build — all pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck

README.md

@@ -16,7 +16,7 @@
 
 - **Per-bottle egress allowlist** — TLS-bumped HTTP/HTTPS chokepoint with a per-manifest host allowlist; per-route path/method/header `matches` filtering; outbound DLP scanning for known tokens and secrets, inbound DLP scanning for prompt-injection attempts; DoH and arbitrary hosts blocked by default.
 - **Per-route token-match policy** — each egress route picks what happens when the outbound DLP catches a token via `dlp.outbound_on_match`: `supervise` (default) holds the request and surfaces it in `./cli.py supervise` for approval (an approved value is remembered for the life of the proxy); `redact` scrubs the value and forwards; `block` is a hard `403`. Cuts false-positive friction without weakening default-deny.
-- **Tokens the agent never sees** — host secrets live in a sidecar; the agent dials `http://sidecar:9099/<path>` and the proxy strips inbound `Authorization` and injects the real token before forwarding. `printenv` in the agent shows proxy URLs only.
+- **Tokens the agent never sees** — host secrets live in a gateway; the agent dials `http://gateway:9099/<path>` and the proxy strips inbound `Authorization` and injects the real token before forwarding. `printenv` in the agent shows proxy URLs only.
 - **Gitleaks-scanned push (git-gate)** — `bottle.git` remotes route through a per-bottle `git daemon` that gitleaks-scans incoming refs pre-receive and forwards clean refs upstream over SSH. The agent never holds the upstream credential.
 - **Manifest-scoped skills + secrets** — each bottle declares its skills, env, git identity, remotes, and egress routes; unknown keys die at load.
 - **Trust boundary at `$HOME`** — bottles (credentials, egress, remotes) live only under `~/.bot-bottle/bottles/`. Repos may ship agents but not bottles, so a cloned repo can't redirect an env var to an attacker host.
@@ -24,17 +24,17 @@
 - **Parallel, isolated bottles** — each bottle runs in its own backend-owned isolation boundary; bottles don't share state or talk to each other.
 - **Provider templates (Claude, Codex)** — `Dockerfile.claude` / `Dockerfile.codex`, or a bottle-supplied Dockerfile. Claude auth via long-lived OAuth token; Codex via opt-in host device-auth forwarding.
 - **gVisor auto-detect** — on Linux hosts where `runsc` is registered with Docker, every bottle launches under it for a userspace syscall barrier; no manifest config required.
-- **Apple Container backend (macOS default when available)** — runs the agent and sidecar bundle with Apple's `container` CLI, using a host-only agent network plus a separate sidecar egress network.
-- **Firecracker backend (Linux default when available)** — runs the agent in a KVM Firecracker microVM reached over SSH on a point-to-point TAP, with the sidecar bundle in Docker. A dedicated, fail-closed `nftables` table isolates the guest, closing the raw DNS/IP exfiltration gap that exists in the legacy Docker backend. Requires KVM (`/dev/kvm`) and a one-time privileged network-pool setup.
+- **Apple Container backend (macOS default when available)** — runs the agent and gateway with Apple's `container` CLI, using a host-only agent network plus a separate gateway egress network.
+- **Firecracker backend (Linux default when available)** — runs the agent in a KVM Firecracker microVM reached over SSH on a point-to-point TAP, with the gateway in Docker. A dedicated, fail-closed `nftables` table isolates the guest, closing the raw DNS/IP exfiltration gap that exists in the legacy Docker backend. Requires KVM (`/dev/kvm`) and a one-time privileged network-pool setup.
 - **Legacy Docker backend** — still available for examples, CI, and hosts without Apple Container or KVM via `BOT_BOTTLE_BACKEND=docker` or `--backend=docker`.
 
 ## Architecture
 
-On the default macOS Apple Container backend, a bottle is an agent container on a host-only internal network plus a sidecar bundle attached to both that internal network and a NAT egress network. The agent gets HTTP(S)_PROXY and CA bundle env vars pointing at the sidecar's internal-network IP, so HTTP/HTTPS traffic flows through the sidecar instead of direct egress. `bottle.git` / git-gate is intentionally deferred on this backend until a safe Apple Container key-delivery path exists.
+On the default macOS Apple Container backend, a bottle is an agent container on a host-only internal network plus a gateway attached to both that internal network and a NAT egress network. The agent gets HTTP(S)_PROXY and CA bundle env vars pointing at the gateway's internal-network IP, so HTTP/HTTPS traffic flows through the gateway instead of direct egress. `bottle.git` / git-gate is intentionally deferred on this backend until a safe Apple Container key-delivery path exists.
 
-On the Firecracker backend, a bottle is an agent microVM plus a Docker sidecar bundle for egress, git-gate, and supervise. The VM reaches the sidecars over a per-bottle point-to-point TAP link; a dedicated fail-closed `nftables` table (`inet bot_bottle_fc`) confines the guest to that link, so nothing leaves the box except through the sidecars. The TAP pool and nft table are provisioned once (root); per-launch needs no privilege.
+On the Firecracker backend, a bottle is an agent microVM plus a Docker gateway for egress, git-gate, and supervise. The VM reaches the gateway over a per-bottle point-to-point TAP link; a dedicated fail-closed `nftables` table (`inet bot_bottle_fc`) confines the guest to that link, so nothing leaves the box except through the gateway. The TAP pool and nft table are provisioned once (root); per-launch needs no privilege.
 
-On the legacy Docker backend, the same logical bottle is two containers per agent: an `agent` container and a `sidecars` container. They share a per-agent Docker `--internal` network; the agent has no default route off-box.
+On the legacy Docker backend, the same logical bottle is two containers per agent: an `agent` container and a `companion containers` container. They share a per-agent Docker `--internal` network; the agent has no default route off-box.
 
 The Docker topology looks like this:
 
@@ -67,11 +67,11 @@ The Docker topology looks like this:
    └─────────────────────────────────────────────────────────────────────┘
 ```
 
-When the agent exits, `cli.py` tears down every sidecar and both networks; nothing about a bottle persists between runs.
+When the agent exits, `cli.py` tears down every gateway and both networks; nothing about a bottle persists between runs.
 
 ## Quickstart
 
-On compatible macOS hosts, the default backend requires Apple's `container` CLI and does not require Docker. The Firecracker backend (Linux) requires Docker on the host for the sidecar bundle plus the `firecracker` binary and KVM. The legacy Docker backend requires Docker. Claude bottles also need a long-lived Claude Code OAuth token (`claude setup-token`) exported as `BOT_BOTTLE_CLAUDE_OAUTH_TOKEN`.
+On compatible macOS hosts, the default backend requires Apple's `container` CLI and does not require Docker. The Firecracker backend (Linux) requires Docker on the host for the gateway plus the `firecracker` binary and KVM. The legacy Docker backend requires Docker. Claude bottles also need a long-lived Claude Code OAuth token (`claude setup-token`) exported as `BOT_BOTTLE_CLAUDE_OAUTH_TOKEN`.
 
 Use `BOT_BOTTLE_BACKEND=docker ./cli.py start <agent>` on hosts where neither Apple Container nor KVM is available and Docker is the desired backend.
 
@@ -81,7 +81,7 @@ On Linux, a KVM-capable host defaults to the Firecracker backend. It needs:
 
 - **`/dev/kvm`** present and accessible. Load `kvm-intel` or `kvm-amd` (and enable virtualization in BIOS/firmware). The invoking user must be in the `kvm` group: `sudo usermod -aG kvm "$USER"` then re-login. bot-bottle preflights this and reports exactly what's missing.
 - **`firecracker`** on `PATH`: grab a release from <https://github.com/firecracker-microvm/firecracker/releases>. Start flows print this pointer when the binary is missing.
-- **Docker** for the sidecar bundle and image build.
+- **Docker** for the gateway and image build.
 - **A one-time privileged network setup** — the per-bottle TAP pool plus the fail-closed `nftables` isolation table. Run `./cli.py backend setup --backend=firecracker` for the host-appropriate config (a NixOS module, a `sudo` script elsewhere); `./cli.py backend status --backend=firecracker` reports what's present, including whether the pool range collides with an existing route. The pool defaults to `10.243.0.0/16` (an obscure RFC-1918 block that dodges docker/libvirt/LAN and, deliberately, Tailscale's `100.64.0.0/10` CGNAT range); override with `BOT_BOTTLE_FC_IP_BASE` if it clashes on your host.
 
 ```sh