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/models/api.py

@@ -74,6 +74,14 @@ class AlertRuleResponse(BaseModel):
 
 class AskRequest(BaseModel):
     question: str
+    services: list[str] | None = None
+    actor: str | None = None
+    operation: str | None = None
+    result: str | None = None
+    start: str | None = None
+    end: str | None = None
+    include_tags: list[str] | None = None
+    exclude_tags: list[str] | None = None
 
 
 class AskEventRef(BaseModel):