refactor(de-sidecar): remove the per-bottle companion-container architecture

The per-agent companion container (the egress/git-gate/supervise data
plane run once per bottle) is the pre-consolidation architecture. Remove
it and disable the backends that still depend on it, per the #385 thread.

- Delete `backend/docker/sidecar_bundle.py`; docker's live path uses the
  consolidated shared gateway, not a per-bottle bundle.
- Disable the firecracker and macos-container backends: their `launch()`
  fails closed (they launched a per-bottle companion; firecracker's
  consolidated relaunch is #354, macos follows). Their `enumerate` return
  empty and `cleanup` drop the companion-container discovery (firecracker
  keeps VMM/run-dir cleanup).
- Fail-close both backends' `egress_apply` reload (it signalled the
  per-bottle container); consolidated egress policy resolves per-request
  against the orchestrator, so gateway-side apply is a follow-up.
- Rename `egress_sidecar_env_entries` → `egress_gateway_env_entries`,
  `SIDECAR_PORTS` → `GATEWAY_PORTS`.
- Move the shared DockerBottlePlan fixture to `tests/unit/_docker_bottle_plan.py`;
  delete tests for the removed launch paths; update cleanup/egress-apply tests.

Docker consolidated launch verified end-to-end (multitenant isolation
integration test passes). macos/firecracker are intentionally disabled.

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

bot_bottle/backend/firecracker/cleanup.py

@@ -1,9 +1,8 @@
 """Cleanup for the Firecracker backend.
 
 Orphans are: firecracker VMM processes whose config lives under our run
-dir, the `bot-bottle-sidecars-*` containers, and the per-bottle run
-dirs. TAP slots free themselves (the flock drops when the launcher
-exits), so there is nothing to reclaim there.
+dir, and the per-bottle run dirs. TAP slots free themselves (the flock
+drops when the launcher exits), so there is nothing to reclaim there.
 """
 
 from __future__ import annotations
@@ -18,8 +17,6 @@ from ...log import info
 from . import util
 from .bottle_cleanup_plan import FirecrackerBottleCleanupPlan
 
-_SIDECAR_PREFIX = "bot-bottle-sidecars-"
-
 
 def _run_root() -> Path:
     return util.cache_dir() / "run"
@@ -46,17 +43,6 @@ def _orphan_vm_pids() -> list[int]:
     return pids
 
 
-def _sidecar_containers() -> list[str]:
-    result = subprocess.run(
-        ["docker", "ps", "-a", "--format", "{{.Names}}",
-         "--filter", f"name={_SIDECAR_PREFIX}"],
-        capture_output=True, text=True, check=False,
-    )
-    if result.returncode != 0:
-        return []
-    return sorted(n.strip() for n in result.stdout.splitlines() if n.strip())
-
-
 def _run_dirs() -> list[str]:
     run_root = _run_root()
     if not run_root.is_dir():
@@ -67,7 +53,6 @@ def _run_dirs() -> list[str]:
 def prepare_cleanup() -> FirecrackerBottleCleanupPlan:
     return FirecrackerBottleCleanupPlan(
         vm_pids=tuple(_orphan_vm_pids()),
-        containers=tuple(_sidecar_containers()),
         run_dirs=tuple(_run_dirs()),
     )
 
@@ -79,12 +64,6 @@ def cleanup(plan: FirecrackerBottleCleanupPlan) -> None:
             os.kill(pid, signal.SIGTERM)
         except ProcessLookupError:
             pass
-    for name in plan.containers:
-        info(f"docker rm -f {name}")
-        subprocess.run(
-            ["docker", "rm", "-f", name],
-            stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, check=False,
-        )
     for path in plan.run_dirs:
         info(f"rm -rf {path}")
         shutil.rmtree(path, ignore_errors=True)