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/settings.py

@@ -1,6 +1,7 @@
 from quart import Blueprint, jsonify, request
 
 from fabledassistant.auth import login_required, get_current_user_id
+from fabledassistant.services.caldav import CALDAV_SETTING_KEYS, get_caldav_config, test_connection
 from fabledassistant.services.llm import get_installed_models
 from fabledassistant.services.settings import get_all_settings, set_settings_batch
 
@@ -32,3 +33,39 @@ async def update_settings_route():
     await set_settings_batch(uid, {k: str(v) for k, v in data.items()})
     settings = await get_all_settings(uid)
     return jsonify(settings)
+
+
+@settings_bp.route("/caldav", methods=["GET"])
+@login_required
+async def get_caldav():
+    uid = get_current_user_id()
+    config = await get_caldav_config(uid)
+    if config.get("caldav_password"):
+        config["caldav_password"] = "********"
+    return jsonify(config)
+
+
+@settings_bp.route("/caldav", methods=["PUT"])
+@login_required
+async def update_caldav():
+    uid = get_current_user_id()
+    data = await request.get_json()
+
+    settings_to_save = {}
+    for key in CALDAV_SETTING_KEYS:
+        if key in data:
+            if key == "caldav_password" and data[key] == "********":
+                continue
+            settings_to_save[key] = str(data[key])
+
+    if settings_to_save:
+        await set_settings_batch(uid, settings_to_save)
+    return jsonify({"status": "ok"})
+
+
+@settings_bp.route("/caldav/test", methods=["POST"])
+@login_required
+async def test_caldav():
+    uid = get_current_user_id()
+    result = await test_connection(uid)
+    return jsonify(result)