feat(settings): propagate user_timezone to briefing scheduler on save

When user_timezone is saved via PUT /api/settings, immediately call
update_user_schedule if briefing is enabled so the scheduler picks up
the new timezone without requiring a restart.

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

src/fabledassistant/routes/settings.py

@@ -7,7 +7,7 @@ from fabledassistant.auth import login_required, get_current_user_id
 from fabledassistant.config import Config
 from fabledassistant.services.caldav import CALDAV_SETTING_KEYS, get_caldav_config, test_connection
 from fabledassistant.services.llm import get_installed_models, _is_private_url
-from fabledassistant.services.settings import delete_setting, get_all_settings, set_settings_batch
+from fabledassistant.services.settings import delete_setting, get_all_settings, get_setting, set_settings_batch
 
 logger = logging.getLogger(__name__)
 
@@ -80,6 +80,18 @@ async def update_settings_route():
     if to_save:
         await set_settings_batch(uid, to_save)
 
+    # When timezone changes, live-patch the briefing scheduler immediately
+    if "user_timezone" in to_save:
+        import json as _json
+        from fabledassistant.services.briefing_scheduler import update_user_schedule
+        config_raw = await get_setting(uid, "briefing_config", "{}")
+        try:
+            config = _json.loads(config_raw) if isinstance(config_raw, str) else {}
+        except Exception:
+            config = {}
+        if config.get("enabled"):
+            update_user_schedule(uid, config, tz_override=to_save["user_timezone"] or None)
+
     if "default_model" in to_save and to_save["default_model"]:
         asyncio.create_task(_prime_kv_cache_bg(uid, to_save["default_model"]))