test: add coverage for orchestrator + gitea client (diff gate 77% → 98%)

Three new unit test modules:
- tests/unit/test_contrib_gitea_client.py — GiteaClient (urllib mocked)
  and GiteaForge delegation
- tests/unit/orchestrator/test_main.py — __main__ run/status commands
- tests/unit/orchestrator/test_bootstrap.py — _token, BotBottleStateStore,
  _to_forge_state/_to_record, make_forge, make_sidecar, build

Augments to existing suites:
- test_events: non-"created" comment action ignored
- test_lifecycle: _iso_now callable, untracked-issue comment ignored,
  untracked-PR closed ignored (covers _find_by_pr return-None path)
- test_runner: destroy command, _default_run via subprocess mock
- test_sidecar: _jsonable dataclass/list branches, OpLog.read on missing
  file, drain_done_events on corrupted file, socket _Handler invalid-JSON
  and empty-line paths, serve() with pre-existing socket path
- test_watchdog: _loop body covered by patching _TICK_SECS to 0.01s
- test_webhook: unknown GET path returns 404

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/orchestrator/test_webhook.py

@@ -150,6 +150,12 @@ class WebhookServerTest(unittest.TestCase):
             self._get("/provenance?owner=x&repo=y&issue=1")
         self.assertEqual(404, ctx.exception.code)
 
+    def test_unknown_get_path_404(self):
+        self._serve()
+        with self.assertRaises(HTTPError) as ctx:
+            self._get("/nope")
+        self.assertEqual(404, ctx.exception.code)
+
 
 if __name__ == "__main__":
     unittest.main()