Add persistent context sidebar, note title fix, and expanded tool suite

Context sidebar + note title:
- ChatView: replace ephemeral context pills with a persistent right-panel sidebar;
  auto-found notes accumulate across turns; attached note shows with pin icon;
  × button excludes a note from future auto-search; hidden on mobile
- routes/chat.py: batch-fetch note titles via get_notes_by_ids() and inject
  context_note_title into each message dict at conversation load time
- notes.py: add get_notes_by_ids() batch fetch helper
- types/chat.ts: add context_note_title field to Message interface
- stores/chat.ts: sendMessage accepts optional 5th arg contextNoteTitle,
  included in optimistic user message
- ChatMessage.vue: context badge shows note title instead of 'Note #N'

Expanded LLM tool suite (all with intent router rules + ToolCallCard display):
- delete_note / delete_task: permanent delete with user confirmation (write tool),
  type-safe (refuse to delete wrong type), clears note context cache on success
- get_note: fetch full note body by query (search_notes returns only 200-char preview)
- list_notes: browse notes by recency/keyword/tags with limit; notes only
- update_note: add tags + tag_mode (replace/add/remove) parameters
- search_notes: add optional type filter ("note" | "task")
- search_todos (CalDAV): keyword-filter todos, companion to list_todos
- caldav.py: add search_todos() built on top of list_todos()
- generation_task.py: register new tools in _WRITE_TOOLS, _TOOL_LABELS, _TOOL_ACTIONS
- llm.py: update available actions list and guidance in system prompt
- intent.py: routing rules for all new tools

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

src/fabledassistant/services/caldav.py

@@ -530,6 +530,21 @@ async def list_todos(
     return await asyncio.to_thread(_list)
 
 
+async def search_todos(
+    user_id: int,
+    query: str,
+    include_completed: bool = False,
+    calendar_name: str | None = None,
+) -> list[dict]:
+    """Search CalDAV todos by keyword in summary or description."""
+    todos = await list_todos(user_id, include_completed=include_completed, calendar_name=calendar_name)
+    q = query.lower()
+    return [
+        t for t in todos
+        if q in t.get("summary", "").lower() or q in (t.get("description") or "").lower()
+    ]
+
+
 async def complete_todo(
     user_id: int,
     query: str,