Add reusable local HTTP job service for Blender add-ons

- Implement JobClient for handling HTTP requests to the JobServer.
- Create ModalJobOperatorBase for managing Blender job lifecycle.
- Introduce JobContext and JobServer for job management and state handling.
- Add ServiceConnection and ServiceController for managing service processes.
- Implement job submission, cancellation, and resource management endpoints in the server.
- Ensure proper error handling and job state updates throughout the service.

tests/test_worker.py

@@ -19,7 +19,7 @@ PROJECT_ROOT = Path(__file__).resolve().parents[1]
 def load_worker():
     specification = importlib.util.spec_from_file_location(
         "snapform_worker",
-        PROJECT_ROOT / "src" / "snapform" / "worker.py",
+        PROJECT_ROOT / "src" / "snapform" / "ai_service" / "jobs.py",
     )
     module = importlib.util.module_from_spec(specification)
     specification.loader.exec_module(module)
@@ -500,18 +500,18 @@ class WorkerTest(unittest.TestCase):
     def test_models_from_r2_roundtrip_preserves_fields(self):
         root = PROJECT_ROOT / ".tmp-models-from-r2"
         model_dir = root / "models" / "DA3"
-        discovery = root / "service.json"
+        runtime_state = root / "runtime.json"
         try:
-            discovery.parent.mkdir(parents=True, exist_ok=True)
-            discovery.write_text(
-                json.dumps({"port": 1, "token": "t"}),
+            runtime_state.parent.mkdir(parents=True, exist_ok=True)
+            runtime_state.write_text(
+                json.dumps({"keep": "value"}),
                 encoding="utf-8",
             )
             self.assertFalse(self.worker._models_from_r2(model_dir))
             self.worker._mark_models_from_r2(model_dir)
             self.assertTrue(self.worker._models_from_r2(model_dir))
-            payload = json.loads(discovery.read_text(encoding="utf-8"))
-            self.assertEqual(payload["port"], 1)
+            payload = json.loads(runtime_state.read_text(encoding="utf-8"))
+            self.assertEqual(payload["keep"], "value")
             self.assertTrue(payload["models_from_r2"])
         finally:
             shutil.rmtree(root, ignore_errors=True)