feat: natural language queries respect UI filters (v1.2.0)

- AskRequest now accepts optional filter fields: services, actor, operation,
  result, start, end, include_tags, exclude_tags
- ask_question merges NL-extracted constraints with explicit UI filters
- Frontend sends active filter state with every ask request
- Show filter hint below ask input when filters are active
- Add tests for service+result filtering and actor filtering in /api/ask

Bump version to 1.2.0

backend/tests/test_ask.py

@@ -277,3 +277,76 @@ class TestAskEndpoint:
         assert data["llm_used"] is False  # Falls back
         assert len(data["events"]) == 1
         assert "Found 1 event" in data["answer"]
+
+    def test_ask_with_explicit_filters(self, client, mock_events_collection):
+        now = datetime.now(UTC)
+        mock_events_collection.insert_one(
+            {
+                "id": "evt-exchange",
+                "timestamp": now.isoformat(),
+                "service": "Exchange",
+                "operation": "Update",
+                "result": "failure",
+                "actor_display": "Alice",
+                "target_displays": ["LAPTOP-001"],
+                "display_summary": "summary",
+                "raw_text": "raw",
+            }
+        )
+        mock_events_collection.insert_one(
+            {
+                "id": "evt-directory",
+                "timestamp": now.isoformat(),
+                "service": "Directory",
+                "operation": "Add user",
+                "result": "success",
+                "actor_display": "Alice",
+                "target_displays": ["LAPTOP-001"],
+                "display_summary": "summary",
+                "raw_text": "raw",
+            }
+        )
+        response = client.post(
+            "/api/ask",
+            json={"question": "What happened to LAPTOP-001?", "services": ["Exchange"], "result": "failure"},
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert data["query_info"]["event_count"] == 1
+        assert data["events"][0]["id"] == "evt-exchange"
+
+    def test_ask_with_explicit_actor_filter(self, client, mock_events_collection):
+        now = datetime.now(UTC)
+        mock_events_collection.insert_one(
+            {
+                "id": "evt-bob",
+                "timestamp": now.isoformat(),
+                "service": "Directory",
+                "operation": "Add user",
+                "result": "success",
+                "actor_display": "Bob",
+                "actor_upn": "bob@example.com",
+                "target_displays": ["USER-001"],
+                "display_summary": "summary",
+                "raw_text": "raw",
+            }
+        )
+        mock_events_collection.insert_one(
+            {
+                "id": "evt-alice",
+                "timestamp": now.isoformat(),
+                "service": "Directory",
+                "operation": "Remove user",
+                "result": "success",
+                "actor_display": "Alice",
+                "actor_upn": "alice@example.com",
+                "target_displays": ["USER-001"],
+                "display_summary": "summary",
+                "raw_text": "raw",
+            }
+        )
+        response = client.post("/api/ask", json={"question": "What happened to USER-001?", "actor": "bob"})
+        assert response.status_code == 200
+        data = response.json()
+        assert data["query_info"]["event_count"] == 1
+        assert data["events"][0]["id"] == "evt-bob"