Item 5 — daily hero prop is a live RULE (biggest model-vs-market disagreement)

The landing hero was a static Jokic "Example" card with a name-length pick and a
hardcoded A- 73% +6.2% fallback. Now it's deterministic and live:

- heroPropService.pickHeroProp reads the pre-graded snapshot and selects the
  prop with the LARGEST |projection - line| gap among A/B grades (conviction,
  not noise) — the read where VYNDR disagrees most with the market, the card
  that makes a stranger argue. No curation, no grading (reads cache → no API
  credits). GET /api/hero-prop (backend) + repointed Next proxy.
- The card shows the disagreement EXPLICITLY: the book's line vs VYNDR's model,
  side by side (model in green), with the real grade timestamp ("Graded 2:14
  PM"). The EXAMPLE chip is gone.
- Empty slate → the MOST RECENT real graded read (flagged "LATEST READ", real
  date). Nothing cached → { available:false } and the card HIDES. No
  hand-written fallback — the Jokic card is deleted. Survives a dead night: a
  live rule shows tonight's real MLB read, never a phantom July NBA card.

7 service tests lock the rule (max-gap, A/B gate, projection/line required,
empty→recent, hidden, cross-sport). colorContract updated to the new
disagreement display. Change-affected suites green, web build exit 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app.js

@@ -216,6 +216,7 @@ app.use('/api/internal', internalRoutes);
 // requireInternalAuth); no Next proxy on purpose — never browser-facing.
 app.use('/api/partners', require('./routes/partners'));
 app.use('/api/founders', require('./routes/founders'));
+app.use('/api/hero-prop', require('./routes/heroProp'));
 
 // Session 10 — Sentry's Express error handler catches uncaught
 // errors from every route mounted above. Must come AFTER routes but