feat(incidents): anonymous report tracking by token + public /track

Gap: fileIncident minted a reporter_token and the filing UI showed it
("the only way to look it up later") but there was no lookup UI.

- lib/incident-logic.ts (pure, tested): publicIncidentView redacts —
  board_only updates, subjects, decision-maker ids dropped; disposition
  only surfaced once decided/closed; status label mapping
- trackIncident: public service-client action (token is a 192-bit
  bearer credential on a UNIQUE column; anon has no RLS path so the
  service client is used AFTER token validation; generic not-found is
  enumeration-safe; board_only filtered at the query AND in logic)
- public /track page + client (also accepts ?token= deep link);
  /track added to middleware PUBLIC_ROUTES
- filing UI now deep-links /track?token=<code>
- trackIncidentSchema; __tests__/incident-tracking.test.ts (6)
- docs: API_REFERENCE + HANDOFF pass-20 (session arc, web-verified
  integration facts, locked forward roadmap, open items incl. the
  still-open production incident-INSERT RLS bug)

343 tests; build verified (Compiled successfully, exit 0).

proxy.ts

@@ -12,6 +12,8 @@ const PUBLIC_ROUTES = [
   '/login',
   '/signup',
   '/join',
+  // Public anonymous-incident status lookup by reporter token.
+  '/track',
   '/auth',
   '/api/health',
   // Public form / waiver fill page. Only /f/[slug] lives here and must be