feat: per-user notifications (ntfy + RSS), deduplicated actions, backfill task

Notifications:
- New /notifications page accessible to all users (ntfy + RSS config)
- ntfy now supports no-auth, Bearer token, and HTTP Basic auth (for ACL-protected self-hosted servers)
- RSS enabled/disabled independently of ntfy; token auto-generated on first GET
- Notification settings removed from admin-only Settings page; replaced with link card
- Sidebar adds Notifications nav link for all users
- notification_dispatcher.py: fan-out now marks RSS events dispatched independently

Action history:
- Migration 0012: deduplicates existing bill_actions rows and adds UNIQUE(bill_id, action_date, action_text)
- congress_poller.py: replaces existence-check inserts with ON CONFLICT DO NOTHING (race-condition safe)
- Added backfill_all_bill_actions task (no date filter) + admin endpoint POST /backfill-all-actions

Authored-By: Jack Levy

PocketVeto — Feature Roadmap.md

@@ -76,3 +76,89 @@
 - [ ] **Source Viewer Option B** — in-app bill text viewer with cited passage highlighted and scroll-to-anchor. Deferred pending UX review of Option A (GovInfo link).
 - [ ] **Raw Diff Panel** — Python `difflib` diff between stored document versions, shown as collapsible "Raw Changes" below amendment brief. Zero API calls. Deferred — AI amendment brief is the primary "what changed" story.
 - [ ] **Shareable Collection Subscriptions** — "Follow this collection" mechanic so other users can subscribe to a public collection and get its bills added to their feed.
+- [ ] Pocket Veto mode (follow stance) — toggle on a bill to treat it as “I don’t want this to pass”; adds to watchlist and triggers milestone alerts (committee report-out, calendared, vote scheduled, passed chamber, etc.)
+- [ ] Pocket Veto notification rules — alert only on advancement milestones + failure outcomes (failed committee / failed floor / stalled)
+- [ ] Follow modes — support Neutral (normal follow) + Pocket Veto now; optional Pocket Boost later
+- [ ] UI: FollowButton becomes FollowMode selector (Neutral / Pocket Veto) with explanation tooltip
+
+
+### PocketVeto function
+
+#### How it should work (so it’s useful and not cringey)
+
+Instead of “follow/unfollow,” each bill gets a **Follow Mode**:
+
+- **Follow** (neutral): “Keep me posted on meaningful changes.”
+    
+- **Pocket Veto** (oppose): “Alert me if this bill is advancing toward passage.”
+    
+- (Optional later) **Pocket Boost** (support): “Alert me when action is needed / when it’s in trouble.” also suggest an action the user can take to let their representatives know that you support this bill.
+    
+
+For Pocket Veto specifically, the key is **threshold alerts**, not spam:
+
+- **Committee referral**
+    
+- **Committee hearing scheduled**
+    
+- **Markup scheduled**
+    
+- **Reported out of committee**
+    
+- **Placed on calendar**
+    
+- **Floor vote scheduled**
+    
+- **Passed chamber**
+    
+- **Conference / reconciliation activity**
+    
+- **Sent to President**
+    
+- **Signed / Vetoed**
+    
+
+And the “failed” side:
+
+- **Failed in committee**
+    
+- **Failed floor vote**
+    
+- **Stalled** (no action for X days while similar bills move)
+    
+
+#### Why it’s valuable for “normal people”
+
+Most people don’t want to follow politics continuously. They want:
+
+- “Tell me if the bad thing is about to happen.”  
+    That’s exactly what Pocket Veto mode does.
+    
+
+#### Guardrail to keep it non-partisan / non-toxic
+
+Make it explicit in UI copy:
+
+- It’s a **personal alert preference**, not a moral label.
+    
+- It doesn’t publish your stance unless you share it.
+    
+
+#### Data model addition (simple)
+
+Add fields to `follows` (or a new table):
+
+- `follow_mode`: `neutral | pocket_veto | pocket_boost`
+    
+- `alert_sensitivity`: `low | medium | high` (optional)
+    
+
+Then alert rules can be:
+
+- neutral: material changes
+    
+- pocket_veto: only “advancing toward passage” milestones
+    
+- pocket_boost: “action points” + milestones
+    
+