feat: East Africa + Southern Africa pills with regional sub-sections

- East Africa pill: merges Uganda + east-africa tags; Uganda pinned first via sub-sections
- Southern Africa pill: covers SA, Namibia, Botswana, Zimbabwe, Zambia, Mozambique; SA/Namibia/Botswana prioritized
- StoryStore.setPill now resets lastSyncedAt to bypass 30s rate-limit on filter switch
- sectionSupplement background fetch populates sparse regional sections in All digest
- SignalFeedView digestContent: flat hero+scroll path for pills without subSections (was showing max 5)
- Theme: removed standalone Uganda pill, wired new sub-section layouts

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

Jarvis/Notifications/NotificationManager.swift

@@ -41,6 +41,11 @@ final class NotificationManager: NSObject, ObservableObject {
     func bootstrap() async {
         center.delegate = self
         await refreshAuthStatus()
+        // Prompt for permission on first launch (.notDetermined).
+        // Re-requesting after denial is a no-op (iOS ignores it) — safe to call every launch.
+        if authStatus == .notDetermined {
+            await requestAuthorization()
+        }
         subscribeToBreakingEvents()
         await applySettings()
     }