feat(briefing): hard-cut tear-down

Backend:
- Delete briefing services (pipeline, scheduler, conversations, profile, tools)
- Delete routes/briefing.py + remove blueprint registration
- Move _get_temp_unit into services/weather.get_temp_unit (reads top-level temp_unit setting)
- Rename briefing_preferences.py → rss_filtering.py (functions are RSS-specific)
- Strip briefing scheduler hooks from app.py
- Strip briefing scheduler call from routes/settings.py
- Update test imports (test_rss_service, test_tz_helpers)

Frontend:
- Delete BriefingView, BriefingSetupWizard, BriefingToolStatusRow
- Strip /briefing route + nav links (AppHeader, KnowledgeView)
- Strip Settings → Briefing tab + state + functions + imports
- Strip briefing-intermediate handling from ChatMessage
- Hide /news route + nav links (NewsView depended on briefing endpoints; orphaned in tree)
- Drop unused useSettingsStore from AppHeader

The Android BriefingScreen lives in a separate repo and is not touched here.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/fabledassistant/routes/settings.py

@@ -94,17 +94,8 @@ 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)
+    # Journal scheduler live-reschedule on timezone change is wired up in
+    # services/journal_scheduler.update_user_schedule (Stage C).
 
     if "default_model" in to_save and to_save["default_model"]:
         asyncio.create_task(_prime_kv_cache_bg(uid, to_save["default_model"]))