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/[locale]/macro/page.tsx

@@ -52,7 +52,7 @@ export async function generateMetadata({
         : 'Macro vibes for crypto. Read what is about to happen before price prints it.',
     },
     alternates: {
-      canonical: `${siteUrl}/${locale}/macro`,
+      canonical: `${siteUrl}/en/macro`,
       languages: {
         en: `${siteUrl}/en/macro`,
         'x-default': `${siteUrl}/en/macro`,