Remove CalDAV todo tools; overhaul quick-capture

- Remove all 6 CalDAV todo tools (create/list/update/complete/delete/search_todos)
  from tools.py definitions, imports, execute_tool branches, intent routing rules,
  generation_task labels/actions, and llm.py system prompt hints. CalDAV event
  tools remain. Todo functions still exist in caldav.py but are no longer exposed.

- Quick-capture now uses a dedicated classify_capture_intent() with a focused
  _CAPTURE_SYSTEM_PROMPT that always routes to a tool (never null). Tool set
  expanded: create_note/task/event + update_note + research_topic.

- research_topic in quick-capture calls run_research_pipeline() directly (no SSE
  buffer). run_research_pipeline() now accepts buf=None; all buf.append_event
  calls are guarded so status events are skipped when no buffer is provided.

- Fallback note now always sets body=text (was empty for texts ≤80 chars).

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

src/fabledassistant/services/generation_task.py

@@ -54,12 +54,6 @@ _TOOL_LABELS: dict[str, str] = {
     "update_event": "Updating calendar event",
     "delete_event": "Removing calendar event",
     "list_calendars": "Listing calendars",
-    "create_todo": "Creating todo",
-    "list_todos": "Listing todos",
-    "search_todos": "Searching todos",
-    "update_todo": "Updating todo",
-    "complete_todo": "Completing todo",
-    "delete_todo": "Removing todo",
     "search_web": "Searching the web",
     "research_topic": "Researching topic",
 }
@@ -68,7 +62,6 @@ _TOOL_LABELS: dict[str, str] = {
 _WRITE_TOOLS: frozenset[str] = frozenset({
     "create_task", "create_note", "update_note", "delete_note", "delete_task",
     "create_event", "update_event", "delete_event",
-    "create_todo", "update_todo", "complete_todo", "delete_todo",
 })
 
 # Action phrases used in the acknowledgment prompt — "You are about to: {action}"
@@ -82,18 +75,12 @@ _TOOL_ACTIONS: dict[str, str] = {
     "list_notes": "list notes",
     "list_tasks": "look up tasks",
     "search_notes": "search through notes",
-    "search_todos": "search calendar todos",
     "create_event": "schedule a calendar event",
     "list_events": "check the calendar",
     "search_events": "search calendar events",
     "update_event": "update a calendar event",
     "delete_event": "remove a calendar event",
     "list_calendars": "list available calendars",
-    "create_todo": "create a calendar todo",
-    "list_todos": "check calendar todos",
-    "update_todo": "update a calendar todo",
-    "complete_todo": "mark a todo complete",
-    "delete_todo": "remove a calendar todo",
 }