Banners: add 125x125 + 336x280, fill skyscrapers; scrollable sidebar

- New 125x125 (square button) and 336x280 (large rectangle) promo banners;
  rectangle branch scales relative so both rectangles look right.
- 160x600 / 120x600 skyscrapers now filled with feature bullets (instant
  payouts, 7 ad formats, earn by viewing, free to join) + CTA.
- Promo tools lists the new sizes; previews cache-busted (?v=3).
- Back-office sidebar is scrollable (overflow-y:auto) so the Legal links at the
  bottom are reachable.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/assets/my.js

@@ -1145,7 +1145,9 @@
       const BANNERS = [
         { file: 'iap-hero-1200x630.png', size: '1200×630 (social / hero)' },
         { file: 'iap-728x90.png', size: '728×90 (leaderboard)' },
+        { file: 'iap-336x280.png', size: '336×280 (large rectangle)' },
         { file: 'iap-300x250.png', size: '300×250 (rectangle)' },
+        { file: 'iap-125x125.png', size: '125×125 (square button)' },
         { file: 'iap-468x60.png', size: '468×60 (banner)' },
         { file: 'iap-160x600.png', size: '160×600 (wide skyscraper)' },
         { file: 'iap-120x600.png', size: '120×600 (skyscraper)' },
@@ -1156,7 +1158,7 @@
         const url = location.origin + '/banners/' + b.file;
         const d = document.createElement('div');
         d.className = 'pb-item';
-        d.innerHTML = '<img src="/banners/' + b.file + '?v=2" alt="InstantAdPay banner ' + b.size + '" loading="lazy">'
+        d.innerHTML = '<img src="/banners/' + b.file + '?v=3" alt="InstantAdPay banner ' + b.size + '" loading="lazy">'
           + '<div class="pb-row"><span class="pb-size">' + b.size + '</span></div>';
         const btn = document.createElement('button');
         btn.className = 'btn small sec';