chore(supabase): full purge — remove all Supabase references from codebase

- Delete supabase/ directory (config.toml, push-migrations.js,
  ADMIN_CREATE_STOP_FIX.sql, 137 archived migration files)
- Remove @supabase/ssr and @supabase/supabase-js from package.json
- Strip *.supabase.co from next.config.ts image hostnames
- Strip https://*.supabase.co from vercel.json CSP connect-src
- Remove 'supabase/**' ignore from eslint.config.mjs
- Clean supabase references from src/lib/db.ts, vitest.config.ts,
  db/seeds/2026-tuxedo-tour-stops.sql, src/actions/storefront.ts,
  scripts/import-tuxedo-stops.ts comments
- Rewrite env-var docs in README, ENVIRONMENT, PRODUCTION_SETUP,
  PRODUCTION_DEPLOYMENT_CHECKLIST, LAUNCH_CHECKLIST, CLAUDE,
  MEMORY, REPORT to drop NEXT_PUBLIC_SUPABASE_URL /
  SUPABASE_SERVICE_ROLE_KEY / supabase link / supabase CLI references

The canonical migration runner is now scripts/migrate.js (uses pg
directly via DATABASE_URL). Migrations live in db/migrations/. The
Supabase CLI is no longer in the codebase. The only remaining
'@supabase/*' in the dep tree is @supabase/auth-js as a transitive
of @neondatabase/auth (Neon Auth / Better Auth).

Final source scan: grep -rln '@supabase\|rest/v1\|supabase\.co'
src/ tests/ db/ scripts/ next.config.ts vercel.json eslint.config.mjs
package.json returns zero. Verification: npm install clean
(11 added, 21 removed, 12 changed), tsc shows same 17 pre-existing
errors (Stripe dahlia API version + fetch preconnect mocks),
vitest 172/175 (3 pre-existing failures in getAdminUser.test.ts),
lint shows same 14 pre-existing errors. Live-tested: dev server
boots in 248ms, public storefronts (/) (/login) (/pricing) (/tuxedo)
(/indian-river-direct) all return 200; /admin/v2?demo=1 reaches 200
after dev_session redirect; storefront renders real brand content.

eslint.config.mjs

@@ -14,7 +14,6 @@ const eslintConfig = defineConfig([
     "next-env.d.ts",
     // Ignore legacy .js scripts that use CommonJS
     "scripts/**",
-    "supabase/**",
     "fix-agents.js",
   ]),
   // Allow setState in useEffect for PWA prompts and client-side state initialization
@@ -26,7 +25,7 @@ const eslintConfig = defineConfig([
   },
   // Relax some rules for legacy code
   {
-    files: ["db/**", "scripts/**", "supabase/**"],
+    files: ["db/**", "scripts/**"],
     rules: {
       "@typescript-eslint/no-require-imports": "off",
       "@typescript-eslint/no-explicit-any": "warn",