fix(macos): review fixes — token on plan, self-heal, symmetric digest, DHCP poll

Addresses findings from a high-effort review of the PRD 0070 macOS backend.

Correctness:
- Stamp identity_token onto MacosContainerBottlePlan after registration. git's
  gitconfig extraHeader and the supervise MCP --header read
  getattr(plan,"identity_token","") at provision time, and both reach the
  gateway on NO_PROXY (bypassing the egress proxy that carries the token). The
  plan never carried it, so /resolve fail-closed and every git fetch/push and
  supervise call from a macOS bottle would have been denied. Registration
  precedes provision(), so — unlike the run-time env — the plan can carry it.
- Self-heal the orchestrator: recreate when it is not (source-current AND
  answering /health), not on the source-hash label alone. A container running
  current code but with a wedged HTTP server was left alone and polled to
  death, failing every launch until manual deletion.
- image_digest and container_image_digest now read the same descriptor.digest
  field; dropped image_digest's id/tag fallback that could yield a value the
  container side can't produce — a permanent mismatch would have recreated the
  shared gateway on every launch (severing every live bottle's egress, since
  the replacement gets a new DHCP address).
- Poll for the agent's and gateway's DHCP address instead of a fatal read
  right after `container run` (there is no --ip; the address can lag start).

Cleanup:
- One _inspect_first + _descriptor_digest behind the four inspect readers.
- Shared bind_mount_spec (util) and host_db_dir (paths) replace per-module
  copies; _GIT_HTTP_PORT now imports git_http_backend.DEFAULT_PORT.
- Drop the dead _url cache / url property and the write-only agent_proxy_url.

Deferred (noted on the PR, not fixed here): the gateway image rebuilding on
every launch (needs source-hash-labeled build), SQLite shared across VM
guests, and the sh -lc profile-override edge — each is design-level or
behavior-risk beyond a review fix.

Verified: real Apple Container bring-up is green and idempotent; 1826 unit
tests pass with `container` absent (CI parity), pyright clean, pylint 9.86.

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

tests/unit/test_macos_gateway.py

@@ -194,6 +194,28 @@ class TestMacosOrchestratorService(unittest.TestCase):
             svc.ensure_running()
         run.assert_not_called()
 
+    def test_wedged_but_current_orchestrator_is_recreated(self) -> None:
+        """A container running the current code but whose HTTP server is dead
+        must be recreated, not left alone and polled to death forever. Checking
+        the source-hash label alone (without health) would strand the host."""
+        svc = MacosOrchestratorService(repo_root=Path("/r"), host_root=Path("/h"))
+        run = Mock()
+        # Unhealthy on the pre-check, healthy once recreated + waited.
+        health = Mock(side_effect=[False, True])
+        with patch(f"{_ORCH}.container_mod") as mod, \
+                patch(f"{_ORCH}.source_hash", return_value="h1"), \
+                patch.object(svc, "_run_orchestrator_container", run), \
+                patch.object(svc, "_ensure_orchestrator_image"), \
+                patch.object(svc, "gateway"), \
+                patch.object(svc, "is_healthy", health):
+            mod.container_is_running.return_value = True
+            mod.inspect_container.return_value = {
+                "configuration": {"labels": {"bot-bottle-orchestrator-source-hash": "h1"}}
+            }
+            mod.try_container_ipv4_on_network.return_value = "192.168.128.2"
+            svc.ensure_running()
+        run.assert_called_once()
+
     def test_changed_source_recreates_the_orchestrator(self) -> None:
         """The control-plane process loaded its bind-mounted source at startup
         and won't reload it."""