refactor(plugins): the display publishes plugin runtime state; retire plugin_state.json (#690)

Stage 2 of the web plugin catalog, after #688.

- The display publishes a plugin runtime snapshot (plugin_runtime.py) to
  the shared cache: per plugin loaded, lifecycle state, a short redacted
  error summary, the version it loaded and when, plus published_at /
  stale_after / running. Written on change (throttled to 10 s; the
  RUNNING/ENABLED flip of an ordinary update is not a change) and once a
  minute otherwise; cleanup() publishes running: false.
- The web reads it back and restores loaded / state / error_info in
  /api/v3/plugins/installed (plus loaded_version, loaded_at and
  data.runtime). Only a live snapshot counts; stale, stopped or missing
  answers null and says which.
- data/plugin_state.json is retired: every reader and writer moved to
  config + disk (desired) or the snapshot (observed). Nothing in it was
  non-derivable, so nothing is migrated and an existing file is left
  unread. The web-side PluginStateManager (state_manager.py) is removed;
  the display's plugin_state.PluginStateManager is the only state machine.
- StateReconciliation compares config + disk with the snapshot, reporting
  enabled-but-not-loaded and older-version-loaded as no_action findings.
- Backups list installed manifests with enabled from config.json.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/web_interface/integration/test_plugin_operations.py

@@ -9,7 +9,6 @@ from pathlib import Path
 
 from src.plugin_system.operation_queue import PluginOperationQueue
 from src.plugin_system.operation_types import OperationType
-from src.plugin_system.state_manager import PluginStateManager
 from src.plugin_system.operation_history import OperationHistory
 
 
@@ -22,12 +21,10 @@ class TestPluginOperationsIntegration(unittest.TestCase):
         
         # Initialize components
         self.operation_queue = PluginOperationQueue(max_history=100)
-        
-        self.state_manager = PluginStateManager(
-            state_file=str(self.temp_dir / "state.json"),
-            auto_save=True
-        )
-        
+
+        # No state manager: installed / enabled / version are read from disk
+        # and config.json, not from a plugin_state.json record.
+
         self.operation_history = OperationHistory(
             history_file=str(self.temp_dir / "history.json"),
             max_records=100
@@ -64,22 +61,15 @@ class TestPluginOperationsIntegration(unittest.TestCase):
             operation_id=operation_id
         )
         self.assertIsNotNone(history_id)
-        
-        # Update state manager
-        self.state_manager.set_plugin_installed(plugin_id, "1.0.0")
-        
-        # Verify state
-        state = self.state_manager.get_plugin_state(plugin_id)
-        self.assertIsNotNone(state)
-        self.assertEqual(state.version, "1.0.0")
-    
+
+        # Verify history
+        history = self.operation_history.get_history(plugin_id=plugin_id)
+        self.assertEqual([r.operation_type for r in history], ["install"])
+
     def test_update_operation_flow(self):
         """Test complete update operation flow."""
         plugin_id = "test-plugin"
         
-        # First, mark as installed
-        self.state_manager.set_plugin_installed(plugin_id, "1.0.0")
-        
         # Enqueue update operation
         operation_id = self.operation_queue.enqueue_operation(
             OperationType.UPDATE,
@@ -97,20 +87,14 @@ class TestPluginOperationsIntegration(unittest.TestCase):
             operation_id=operation_id
         )
         
-        # Update state
-        self.state_manager.update_plugin_state(plugin_id, {"version": "2.0.0"})
-        
-        # Verify state
-        state = self.state_manager.get_plugin_state(plugin_id)
-        self.assertEqual(state.version, "2.0.0")
-    
+        # Verify history
+        history = self.operation_history.get_history(plugin_id=plugin_id)
+        self.assertEqual([r.operation_type for r in history], ["update"])
+
     def test_uninstall_operation_flow(self):
         """Test complete uninstall operation flow."""
         plugin_id = "test-plugin"
         
-        # First, mark as installed
-        self.state_manager.set_plugin_installed(plugin_id, "1.0.0")
-        
         # Enqueue uninstall operation
         operation_id = self.operation_queue.enqueue_operation(
             OperationType.UNINSTALL,
@@ -127,13 +111,10 @@ class TestPluginOperationsIntegration(unittest.TestCase):
             operation_id=operation_id
         )
         
-        # Update state - remove plugin state
-        self.state_manager.remove_plugin_state(plugin_id)
-        
-        # Verify state
-        state = self.state_manager.get_plugin_state(plugin_id)
-        self.assertIsNone(state)
-    
+        # Verify history
+        history = self.operation_history.get_history(plugin_id=plugin_id)
+        self.assertEqual([r.operation_type for r in history], ["uninstall"])
+
     def test_operation_history_tracking(self):
         """Test that operations are tracked in history."""
         plugin_id = "test-plugin"