Add CalDAV calendar integration, LLM-suggested tags, and settings refinements

- CalDAV integration: per-user calendar config, create/list/search events
  via caldav library, LLM tools for calendar operations from chat
- LLM-suggested tags: new tag_suggestions service prompts LLM with existing
  tags and note content to suggest 3-5 relevant tags; exposed via API
  endpoints (suggest-tags, append-tag); integrated into editor views
  (suggest button + clickable pills) and chat tool calls (pills in
  ToolCallCard with one-click apply)
- Settings/model UI refinements, generation task improvements

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

src/fabledassistant/routes/notes.py

@@ -27,6 +27,7 @@ from fabledassistant.services.notes import (
     update_note,
 )
 from fabledassistant.services.settings import get_setting
+from fabledassistant.services.tag_suggestions import suggest_tags
 from fabledassistant.utils.tags import extract_tags
 
 logger = logging.getLogger(__name__)
@@ -95,6 +96,37 @@ async def list_tags_route():
     return jsonify({"tags": tags})
 
 
+@notes_bp.route("/suggest-tags", methods=["POST"])
+@login_required
+async def suggest_tags_route():
+    uid = get_current_user_id()
+    data = await request.get_json()
+    title = data.get("title", "")
+    body = data.get("body", "")
+    tags = await suggest_tags(uid, title, body)
+    return jsonify({"suggested_tags": tags})
+
+
+@notes_bp.route("/<int:note_id>/append-tag", methods=["POST"])
+@login_required
+async def append_tag_route(note_id: int):
+    uid = get_current_user_id()
+    data = await request.get_json()
+    tag = data.get("tag", "").strip()
+    if not tag:
+        return jsonify({"error": "tag is required"}), 400
+
+    note = await get_note(uid, note_id)
+    if note is None:
+        return jsonify({"error": "Note not found"}), 404
+
+    # Append #tag to body
+    new_body = note.body.rstrip() + f"\n#{tag}" if note.body else f"#{tag}"
+    tags = extract_tags(new_body)
+    updated = await update_note(uid, note_id, body=new_body, tags=tags)
+    return jsonify(updated.to_dict())
+
+
 @notes_bp.route("/by-title", methods=["GET"])
 @login_required
 async def get_note_by_title_route():