feat(docker): consolidate to single infra container under gateway_init supervise tree

Collapses the two-container Docker model (gateway + orchestrator) into one
bot-bottle-infra container, matching the macOS and Firecracker backends.

- Dockerfile.infra: now a shared gateway+orchestrator base (COPY bot_bottle
  from orchestrator build, no CMD override)
- Dockerfile.infra.fc: new Firecracker-specific layer (buildah/crun/netavark)
- gateway_init: adds orchestrator daemon with _OPT_IN_DAEMONS gating so it
  only starts when BOT_BOTTLE_GATEWAY_DAEMONS explicitly includes it
- orchestrator/lifecycle: OrchestratorService manages one infra container;
  builds orchestrator (intermediate) then infra; live source bind-mounted at
  /bot-bottle-src with PYTHONPATH so the subprocess uses the checkout
- backend/consolidated_util: extracts provision_bottle + teardown_consolidated
  shared across all three backends; removes duplication in docker/fc/macos
  consolidated_launch modules
- firecracker/infra_vm: builds four images (orchestrator→gateway→infra→infra.fc)
- All unit tests updated and passing (1878 tests)
- PRD status: Draft → Active

tests/unit/test_infra_artifact.py

@@ -96,7 +96,7 @@ class TestVersionInputs(unittest.TestCase):
         (pkg / "app.py").write_text("print('hi')\n")
         (pkg / "egress_entrypoint.sh").write_text("#!/bin/sh\nexec mitmdump\n")
         (pkg / "netpool.defaults.env").write_text("FOO=1\n")
-        for name in ("Dockerfile.orchestrator", "Dockerfile.gateway", "Dockerfile.infra"):
+        for name in ("Dockerfile.orchestrator", "Dockerfile.gateway", "Dockerfile.infra", "Dockerfile.infra.fc"):
             (root / name).write_text(f"FROM scratch  # {name}\n")
         (root / "pyproject.toml").write_text("[project]\nname = 'bot-bottle'\n")