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>

frontend/src/components/AppHeader.vue

@@ -5,7 +5,6 @@ import { useTheme } from "@/composables/useTheme";
 import { useShortcuts } from "@/composables/useShortcuts";
 import { useAuthStore } from "@/stores/auth";
 import { useChatStore } from "@/stores/chat";
-import { useSettingsStore } from "@/stores/settings";
 import AppLogo from "@/components/AppLogo.vue";
 import NotificationBell from "@/components/NotificationBell.vue";
 
@@ -13,7 +12,6 @@ const { theme, toggleTheme } = useTheme();
 const { toggleShortcuts } = useShortcuts();
 const authStore = useAuthStore();
 const chatStore = useChatStore();
-const settingsStore = useSettingsStore();
 const router = useRouter();
 const route = useRoute();
 
@@ -78,9 +76,7 @@ router.afterEach(() => {
         <div class="nav-pill-bar">
           <router-link to="/" class="nav-link" :class="{ 'router-link-active': isKnowledgeActive }">Knowledge</router-link>
           <router-link to="/chat" :class="['nav-link', { 'router-link-active': isChatActive }]">Chat</router-link>
-          <router-link to="/briefing" class="nav-link">Briefing</router-link>
           <router-link to="/calendar" class="nav-link">Calendar</router-link>
-          <router-link v-if="settingsStore.rssEnabled" to="/news" class="nav-link">News</router-link>
           <router-link to="/projects" class="nav-link">Projects</router-link>
         </div>
       </div>
@@ -127,10 +123,8 @@ router.afterEach(() => {
     <div v-if="mobileMenuOpen" class="mobile-menu">
       <router-link to="/" class="nav-link" :class="{ 'router-link-active': isKnowledgeActive }">Knowledge</router-link>
       <router-link to="/chat" :class="['nav-link', { 'router-link-active': isChatActive }]">Chat</router-link>
-      <router-link to="/briefing" class="nav-link">Briefing</router-link>
       <router-link to="/calendar" class="nav-link">Calendar</router-link>
       <router-link to="/projects" class="nav-link">Projects</router-link>
-      <router-link v-if="settingsStore.rssEnabled" to="/news" class="nav-link">News</router-link>
       <router-link to="/shared" class="nav-link">Shared</router-link>
       <div class="mobile-divider"></div>
       <router-link to="/settings" class="nav-link">Settings</router-link>