Video ads (watch-to-earn): duration-tiered pricing, escape-proof player, per-view charge

- New 'video' campaign type; MP4/WebM upload or direct https link + required-watch tier (10/30/60s → 3/7/12 cr per view; viewer earns 1/2/4)
- Composer: video fields, tier dropdown, live price hint
- Earn credits > Watch videos sub-tab: no-seek player, server-clock watch floor, daily cap, self-exclusion, single-use tokens
- media-src CSP for direct-link/hosted video; video skips frame-check

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

db.js

@@ -89,6 +89,7 @@ async function bootstrap() {
     last_ts BIGINT NOT NULL DEFAULT 0,
     PRIMARY KEY (email, day)
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4`);
+  await alterSafe('ALTER TABLE daily_views ADD COLUMN video_count INT NOT NULL DEFAULT 0'); // watch-to-earn videos/day
   await q(`CREATE TABLE IF NOT EXISTS solo_inbox (
     id INT AUTO_INCREMENT PRIMARY KEY,
     campaign_id INT NOT NULL,