refactor(gateway): move the data-plane daemons into a bot_bottle.gateway package

Separate the gateway (data plane) from the orchestrator (control plane) at the
module level. The gateway runtime files move out of the package root — and the
backend-neutral Gateway lifecycle ABC + GATEWAY_* constants move out of
orchestrator/ — into a new bot_bottle/gateway/ package:

  gateway/__init__.py      (was orchestrator/gateway.py: Gateway ABC + consts
                            + rotate_gateway_ca)
  gateway/gateway_init.py  (the PID-1 daemon supervisor)
  gateway/egress_addon.py, egress_addon_core.py, egress_dlp_config.py,
          dlp_detectors.py            (the egress mitmproxy daemon)
  gateway/git_http_backend.py         (the git-http daemon)
  gateway/git_gate_render.py          (the git-gate pre-receive rendering)
  gateway/supervise_server.py         (the supervise MCP daemon)
  gateway/policy_resolver.py          (the data-plane control-plane RPC client)

orchestrator/ now holds only control-plane files. The shared plan/types/auth
layer (egress.py=EgressPlan, git_gate.py=GitGatePlan, supervise.py,
supervise_types.py, control_auth.py) and the launch-time git-gate provisioning
helpers stay at root, so orchestrator/ and backend/ still own them.

Because these daemons are invoked as `python3 -m bot_bottle.<name>`, loaded flat
by mitmproxy, and referenced in Dockerfile.gateway, the move updates more than
Python imports: the `-m` invocations (firecracker/macOS infra scripts), the
Dockerfile.gateway addon shim + ENTRYPOINT, gateway_init's _DAEMONS module
paths, and the git-gate CGI heredocs all now point at bot_bottle.gateway.*.

No behavior change; full unit suite green (2251).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

bot_bottle/supervise.py

@@ -1,7 +1,7 @@
 """Per-bottle supervise plane (PRD 0013).
 
 The supervise plane is the per-bottle MCP daemon plus its host-side
-queue/audit support. The daemon (bot_bottle.supervise_server)
+queue/audit support. The daemon (bot_bottle.gateway.supervise_server)
 sits on the bottle's internal network and exposes MCP tools the agent
 calls when it needs an operator-reviewed egress change:
 
@@ -18,7 +18,7 @@ the response and returns `{status, notes}` to the agent.
 This module defines the host-side library: dataclasses for the queue
 record shapes, queue read/write helpers, the audit log writer, and the
 diff renderer. The in-gateway daemon lives in
-bot_bottle/supervise_server.py; the supervise daemon's container
+bot_bottle/gateway/supervise_server.py; the supervise daemon's container
 lifecycle is owned by the gateway (PRD 0024).
 
 For 0013 the supervisor's approval handlers are deliberately no-ops: