fix(seo/geo): canonical URLs, OG KOL count, FAQ key-storage copy, expand llms.txt

SEO fixes:
- canonical on trump/macro/kol pages now hardcodes /en/ instead of
  /${locale}/ — prevents /zh/* routes (i18n shelved, routes still resolve)
  from generating duplicate-content signals pointing to /zh/ canonicals
- OG image: "15 KOL feeds" → "19" (matches kol_substack.py KOL_FEEDS count)
- FAQ JSON-LD: corrected API key storage description ("stored encrypted in
  your browser's local settings" was wrong — key is server-side encrypted,
  not stored in the browser)

GEO (Generative Engine Optimization):
- llms.txt fully rewritten: +full KOL list (all 19 named), +explicit
  differentiation section, +who-this-is-for, +technology stack detail
  (model names, price sources, DB), +Hyperliquid and isolated-margin
  definitions. AI crawlers (Perplexity, ChatGPT, Claude) use this file
  directly when answering questions about the product.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/layout.tsx

@@ -214,7 +214,7 @@ const jsonLd = {
           name: 'Does Trump Alpha store my trading keys?',
           acceptedAnswer: {
             '@type': 'Answer',
-            text: 'Your Hyperliquid API key is stored encrypted in your browser\'s local settings and sent only to the Trump Alpha backend to execute trades. The key is scoped to trade-only permissions — it cannot withdraw funds. We never ask for your MetaMask seed phrase or any wallet private key.',
+            text: 'Your Hyperliquid API key is encrypted and stored securely on the Trump Alpha server — it never sits in your browser. The key is scoped to trade-only permissions and cannot withdraw funds. We never ask for your MetaMask seed phrase or any wallet private key.',
           },
         },
       ],