feat(backend): reconcile running bottles' CA on gateway bring-up (0081)

Add `attach_bottled_agents_to_gateway()` as an `@abc.abstractmethod` on
`BottleBackend` and implement the first reconcile step across all three
backends: on a gateway cold boot, replace every already-running agent's
trusted CA with the freshly-minted gateway CA. Reconciling running bottles
is a backend responsibility (only the backend can enumerate its agents and
reach them — firecracker over SSH, docker/macOS over exec/cp), so making it
an abstract method keeps the fix cross-backend by construction.

The gateway rootfs is ephemeral, so a rebuild mints a new CA that every
running bottle distrusts (SSL verification fails — #510). This reconcile is
what distributes the fresh CA, so a routine gateway rebuild now doubles as a
free CA rotation. Per-bottle steps are best-effort: one unreachable or
malformed bottle is logged and skipped, never blocking the others.

Trigger — `Gateway.connect_to_orchestrator` now returns a cold-boot bool
(True when it actually (re)brought the gateway up, False when a healthy
current gateway was left untouched); each infra `ensure_running` gates the
reconcile on it, so it fires exactly on cold boot and never on an adopt.

Git-gate re-provision and egress-token restore fold into this same reconcile
on the same trigger in follow-up PRs (#516).

Refs #516. Addresses #510.

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

tests/unit/test_orchestrator_gateway.py

@@ -86,9 +86,12 @@ class TestDockerGateway(unittest.TestCase):
             return _proc()
 
         with patch(_RUN_DOCKER, side_effect=fake):
-            self.sc.connect_to_orchestrator(_ORCH_URL, _TOKEN)
+            cold_booted = self.sc.connect_to_orchestrator(_ORCH_URL, _TOKEN)
         self.assertEqual([], [c for c in calls if c[:2] == ["docker", "run"]])
         self.assertEqual([], [c for c in calls if c[:2] == ["docker", "rm"]])
+        # A healthy current gateway left untouched is not a cold boot — the
+        # bring-up flow skips the running-bottle reconcile (PRD 0081).
+        self.assertFalse(cold_booted)
 
     def test_ensure_running_recreates_when_image_is_stale(self) -> None:
         # Running, but the container was built from an OLD image → recreate so
@@ -106,9 +109,12 @@ class TestDockerGateway(unittest.TestCase):
             return _proc()
 
         with patch(_RUN_DOCKER, side_effect=fake):
-            self.sc.connect_to_orchestrator(_ORCH_URL, _TOKEN)
+            cold_booted = self.sc.connect_to_orchestrator(_ORCH_URL, _TOKEN)
         self.assertEqual(1, len([c for c in calls if c[:2] == ["docker", "run"]]))
         self.assertTrue(any(c[:2] == ["docker", "rm"] for c in calls))
+        # A recreated container minted/mounted its CA afresh — a cold boot that
+        # triggers the running-bottle reconcile (PRD 0081).
+        self.assertTrue(cold_booted)
 
     def test_ensure_running_starts_the_singleton_when_absent(self) -> None:
         calls: list[list[str]] = []
@@ -118,7 +124,8 @@ class TestDockerGateway(unittest.TestCase):
             return _proc(stdout="") if argv[:2] == ["docker", "ps"] else _proc()
 
         with patch(_RUN_DOCKER, side_effect=fake):
-            self.sc.connect_to_orchestrator(_ORCH_URL, _TOKEN)
+            cold_booted = self.sc.connect_to_orchestrator(_ORCH_URL, _TOKEN)
+        self.assertTrue(cold_booted)  # started fresh → reconcile running bottles
 
         runs = [c for c in calls if c[:2] == ["docker", "run"]]
         self.assertEqual(1, len(runs))