feat(notifications): follow modes, milestone alerts, notification enhancements

Follow Modes (neutral / pocket_veto / pocket_boost):
- Alembic migration 0013 adds follow_mode column to follows table
- FollowButton rewritten as mode-aware dropdown for bills; simple toggle for members/topics
- PATCH /api/follows/{id}/mode endpoint with validation
- Dispatcher filters pocket_veto follows (suppress new_document/new_amendment events)
- Dispatcher adds ntfy Actions header for pocket_boost follows

Change-driven (milestone) Alerts:
- New notification_utils.py with shared emit helpers and 30-min dedup
- congress_poller emits bill_updated events on milestone action text
- llm_processor replaced with shared emit util (also notifies member/topic followers)

Notification Enhancements:
- ntfy priority levels (high for bill_updated, default for others)
- Quiet hours (UTC): dispatcher holds events outside allowed window
- Digest mode (daily/weekly): send_notification_digest Celery beat task
- Notification history endpoint + Recent Alerts UI section
- Enriched following page (bill titles, member photos/details via sub-components)
- Follow mode test buttons in admin settings panel

Infrastructure:
- nginx: switch upstream blocks to set $variable proxy_pass so Docker DNS
  re-resolves upstream IPs after container rebuilds (valid=10s)
- TROUBLESHOOTING.md documenting common Docker/nginx/postgres gotchas

Authored-By: Jack Levy

frontend/lib/types.ts

@@ -138,6 +138,7 @@ export interface Follow {
   id: number;
   follow_type: "bill" | "member" | "topic";
   follow_value: string;
+  follow_mode: "neutral" | "pocket_veto" | "pocket_boost";
   created_at: string;
 }
 
@@ -164,4 +165,22 @@ export interface NotificationSettings {
   ntfy_enabled: boolean;
   rss_enabled: boolean;
   rss_token: string | null;
+  digest_enabled: boolean;
+  digest_frequency: "daily" | "weekly";
+  quiet_hours_start: number | null;
+  quiet_hours_end: number | null;
+}
+
+export interface NotificationEvent {
+  id: number;
+  bill_id: string;
+  event_type: "new_document" | "new_amendment" | "bill_updated";
+  payload: {
+    bill_title?: string;
+    bill_label?: string;
+    brief_summary?: string;
+    bill_url?: string;
+  } | null;
+  dispatched_at: string | null;
+  created_at: string;
 }