fix(security): authenticate the orchestrator control plane (issue #400 Critical)

The control plane had no caller authentication — dispatch() routed every
request straight through, and the only guards anywhere were the
(source_ip, identity_token) checks inside /resolve and /attribute, which
authenticate the *bottle* a request is about, not the *caller*. On the
consolidated backends the agent shares a network with the control-plane port
(macOS: the infra container runs 8099 on the agent's --internal network;
docker: the orchestrator container sits on the shared gateway network), so a
prompt-injected agent could GET /bottles (enumerate siblings + policies),
PUT /bottles/<id>/policy (rewrite its own egress allowlist to allow-all),
POST /resolve (read the injected upstream credentials it's never meant to
see), and POST /supervise/respond (self-approve its own proposals). Every
README guarantee collapsed to the agent's discretion.

Fix: a per-host control-plane secret required on every route but GET /health,
compared with hmac.compare_digest. It is held only by the trusted callers and
never handed to an agent:
- minted + persisted 0600 at <root>/control-plane-token (paths.host_control_plane_token);
- injected as $BOT_BOTTLE_CONTROL_PLANE_TOKEN into the orchestrator + gateway
  containers via bare `--env NAME` (value inherited from the launch process,
  so it never lands on argv or in `container/docker inspect`);
- presented by the gateway's PolicyResolver (reads the env) on /resolve, and by
  the host CLI's OrchestratorClient (reads the host file) on every call.

The agent container is never given the env var or the host file, so from a
bottle every /bottles*, /resolve, /attribute, and /supervise/* call now
returns 401 — closing the enumeration, allowlist-rewrite, credential-lift, and
self-approval. The existing (source_ip, identity_token) checks stay as
defense-in-depth.

Enforced when configured: macOS + docker inject the secret (→ enforced). With
no secret set the server runs open and warns loudly at startup — a
fail-visible fallback for the unit suite and for Firecracker, whose
port-scoped nft already blocks agents from 8099 (wiring the secret into its
infra-VM init is a clean fast-follow, left out here to avoid churning the
prebuilt-artifact hash).

Verified end-to-end on real Apple Container: infra comes up healthy, the host
CLI (with the secret) lists bottles while an unauthenticated GET /bottles gets
401, all five issue-#400 attacks from inside the agent get 401, and egress
policy still works (200 allowed / 403 denied) — proving the gateway
authenticates to /resolve with the secret. 1829 unit tests pass, pyright
clean, pylint 9.91.

Refs #400.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

bot_bottle/backend/macos_container/infra.py

@@ -33,6 +33,7 @@ digest check.
 
 from __future__ import annotations
 
+import os
 import time
 import urllib.error
 import urllib.request
@@ -47,7 +48,11 @@ from ...orchestrator.lifecycle import (
     OrchestratorStartError,
     source_hash,
 )
-from ...paths import HOST_DB_FILENAME
+from ...paths import (
+    CONTROL_PLANE_TOKEN_ENV,
+    HOST_DB_FILENAME,
+    host_control_plane_token,
+)
 from . import util as container_mod
 from .gateway import (
     DEFAULT_CA_TIMEOUT_SECONDS,
@@ -220,11 +225,19 @@ class MacosInfraService:
             # Baked onto the container so `_source_current` can detect a real
             # control-plane code change and recreate.
             "--env", f"BOT_BOTTLE_SOURCE_HASH={current_hash}",
+            # The control-plane secret, for BOTH the control plane (to require
+            # it) and the gateway's PolicyResolver (to present it) — they share
+            # this one container. Bare `--env NAME` inherits the value from the
+            # run process below, so the secret never lands on argv or in
+            # `container inspect`'s command line. The agent runs in a SEPARATE
+            # container that is never given this var, which is the whole point.
+            "--env", CONTROL_PLANE_TOKEN_ENV,
             "--entrypoint", "sh",
             self.image,
             "-c", _init_script(self.port),
         ]
-        result = container_mod.run_container_argv(argv)
+        run_env = {**os.environ, CONTROL_PLANE_TOKEN_ENV: host_control_plane_token()}
+        result = container_mod.run_container_argv(argv, env=run_env)
         if result.returncode != 0:
             raise OrchestratorStartError(
                 f"infra container failed to start: "