feat(prd-0081): reprovision CA, git-gate, and egress tokens on gateway bring-up

On a Firecracker gateway cold boot, reconcile every live agent VM against
the fresh gateway: push the new mitmproxy CA into each agent's trust store,
re-provision git-gate repos/creds from the persisted upstreams snapshot,
and restore egress tokens. Per-bottle failures are logged and skipped so
one unreachable VM does not block the rest.

New modules / changes:
- backend/firecracker/reconcile.py: attach_bottled_agents_to_gateway,
  _push_ca, _reprovision_git_gate, _guest_ip_from_config
- git_gate/provision.py: write upstreams.json after key provisioning so
  the bring-up reconcile can reconstruct the upstream table without the
  manifest
- backend/firecracker/infra.py: call attach_bottled_agents_to_gateway in
  the cold-boot branch of ensure_running()
- backend/base.py: no-op default on BottleBackend
- backend/firecracker/consolidated_launch.py: remove superseded
  _reprovision_running_bottles / _guest_ip_from_config
- orchestrator: OrchestratorCore.update_agent_secret + POST
  /bottles/<id>/secret + client.update_agent_secret (single-secret
  in-place update, the reusable primitive from the 2026-07-26 hotfix)
- tests: 15 new tests in test_firecracker_reconcile.py; updated
  test_firecracker_infra.py cold-boot cases; stale FC reprovision tests
  removed from test_backend_secret_reprovision.py

Closes #516.

bot_bottle/backend/docker/gateway.py

@@ -89,10 +89,6 @@ class DockerGateway(Gateway):
         when no dockerfile is configured (a pre-pulled image). BOT_BOTTLE_NO_CACHE
         forces a full rebuild (parity with `start --no-cache`)."""
         if self._dockerfile is None:
-            proc = run_docker(["docker", "pull", self.image_ref])
-            if proc.returncode != 0:
-                raise GatewayError(
-                    f"gateway image pull failed: {proc.stderr.strip()}")
             return
         context = self._build_context or resources.build_root()
         argv = ["docker", "build", "-t", self.image_ref,

bot_bottle/backend/docker/infra.py

@@ -34,7 +34,6 @@ from .orchestrator import (
     ORCHESTRATOR_NETWORK,
 )
 from ... import resources
-from ... import release_manifest
 from ...gateway import (
     GATEWAY_IMAGE,
     GATEWAY_NAME,
@@ -91,14 +90,6 @@ class DockerInfraService(InfraService):
         self._orchestrator_name = orchestrator_name
         self._orchestrator_label = orchestrator_label
         self._gateway_name = gateway_name
-        resolved_orchestrator, orchestrator_local = release_manifest.oci_image(
-            "orchestrator", orchestrator_image)
-        resolved_gateway, gateway_local = release_manifest.oci_image(
-            "gateway", gateway_image)
-        self.orchestrator_image = resolved_orchestrator
-        self.gateway_image = resolved_gateway
-        self._orchestrator_local = orchestrator_local
-        self._gateway_local = gateway_local
 
     def orchestrator(self) -> DockerOrchestrator:
         """The control-plane service. Cheap to reconstruct — `ensure_built`
@@ -113,8 +104,6 @@ class DockerInfraService(InfraService):
             repo_root=self._repo_root,
             host_root=self._host_root,
             root_mount_source=self._root_mount_source,
-            dockerfile=(
-                "Dockerfile.orchestrator" if self._orchestrator_local else None),
         )
 
     def gateway(self) -> DockerGateway:
@@ -130,7 +119,6 @@ class DockerInfraService(InfraService):
             control_network=self.control_network,
             build_context=self._repo_root,
             ca_mount_source=self._gateway_ca_mount_source,
-            dockerfile="Dockerfile.gateway" if self._gateway_local else None,
         )
 
     def ensure_running(
@@ -144,8 +132,8 @@ class DockerInfraService(InfraService):
         gateway = self.gateway()
         # Build both images (cache-aware; a no-op when nothing changed) before
         # bringing either plane up.
-        orchestrator.ensure_available()
-        gateway.ensure_available()
+        orchestrator.ensure_built()
+        gateway.ensure_built()
 
         orchestrator.ensure_running(startup_timeout=startup_timeout)
 

bot_bottle/backend/docker/launch.py

@@ -84,15 +84,6 @@ def build_or_load_images(plan: DockerBottlePlan) -> BottleImages:
             )
         info(f"using cached agent image {plan.image!r}")
         return BottleImages(agent=plan.image)
-    if "@sha256:" in plan.image:
-        pulled = docker_mod.run_docker(["docker", "pull", plan.image])
-        if pulled.returncode != 0:
-            die(f"pulling packaged agent image {plan.image!r} failed: "
-                f"{pulled.stderr.strip()}")
-        docker_mod.verify_agent_image(
-            plan.image, runtime_for(plan.agent_provider_template).smoke_test,
-        )
-        return BottleImages(agent=plan.image)
     docker_mod.build_image(plan.image, str(resources.build_root()), dockerfile=plan.dockerfile_path)
     docker_mod.verify_agent_image(
         plan.image, runtime_for(plan.agent_provider_template).smoke_test,

bot_bottle/backend/docker/orchestrator.py

@@ -125,10 +125,6 @@ class DockerOrchestrator(Orchestrator):
         no-op when nothing changed). No-op when no dockerfile is configured (a
         pre-pulled image). BOT_BOTTLE_NO_CACHE forces a full rebuild."""
         if self._dockerfile is None:
-            proc = run_docker(["docker", "pull", self.image_ref])
-            if proc.returncode != 0:
-                raise GatewayError(
-                    f"orchestrator image pull failed: {proc.stderr.strip()}")
             return
         argv = ["docker", "build", "-t", self.image_ref,
                 "-f", str(self._repo_root / self._dockerfile),