docs: overhaul documentation + add deployment guides

- ARCHITECTURE.md: update for v0.9.0/v0.9.3 — collections schema,
  collection_bills schema, alert_filters in notification_prefs,
  action_category in notification payload, migrations 0015/0016,
  /api/collections + /api/share endpoints, updated pages table,
  pipeline flow reflects categorize_action(), v0.9.0 and v0.9.3
  feature history entries
- ROADMAP.md: new file merging "MVP threshold" and "Feature Roadmap"
  docs into one clean shipped/upcoming/backlog structure with v1.0
  definition; removes stale design notes and duplicate entries
- DEPLOYING.md: new — prerequisites, .env setup, first run, admin
  account, domain/SSL with Caddy, useful commands
- UPDATING.md: new — SSH setup, manual deploy, deploy script, Gitea
  webhook + webhook listener, rollback procedure, env-only updates
- Delete: "MVP threshold this make v1 complete.md" and
  "PocketVeto — Feature Roadmap.md" (superseded by ROADMAP.md)
- how-it-works/page.tsx: accurate per-mode default alert sets,
  Alert Filters callout linking to Notifications settings
- notifications/page.tsx: Follow mode default includes amendment filed;
  Pocket Veto default excludes calendar placement

Authored-By: Jack Levy

frontend/app/notifications/page.tsx

@@ -49,7 +49,7 @@ const MODES = [
     key: "neutral",
     label: "Follow",
     description: "Bills you follow in standard mode",
-    preset: { new_document: true,  new_amendment: false, vote: true,  presidential: true,  committee_report: true,  calendar: false, procedural: false, referral: false },
+    preset: { new_document: true,  new_amendment: true,  vote: true,  presidential: true,  committee_report: true,  calendar: false, procedural: false, referral: false },
   },
   {
     key: "pocket_veto",