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.

ENVIRONMENT.md

@@ -10,15 +10,6 @@ Copy `.env.example` → `.env.local` and fill in the values.
 
 These are safe to commit and can be used in client bundles. Prefix with `NEXT_PUBLIC_`.
 
-### `NEXT_PUBLIC_SUPABASE_URL`
-Your Supabase project URL.
-- **Where to get:** Supabase Dashboard → Project Settings → API → Project URL
-- **Example:** `https://abc123.supabase.co`
-
-### `NEXT_PUBLIC_SUPABASE_ANON_KEY`
-Supabase anonymous (anon) key — safe for client-side use.
-- **Where to get:** Supabase Dashboard → Project Settings → API → anon key
-
 ### `NEXT_PUBLIC_BASE_URL`
 The base URL of your deployment. Used for OAuth redirects and webhook URLs.
 - **Local:** `http://localhost:3000`
@@ -40,12 +31,16 @@ Set to a brand slug to hide other brand routes in single-brand mode.
 
 **Never prefix with `NEXT_PUBLIC_`**. These must only be accessed in Server Components, Server Actions, or API Routes.
 
-### Supabase
+### Database
 
-#### `SUPABASE_SERVICE_ROLE_KEY`
-Full service role key — grants DB admin access bypassing RLS.
-- **Where to get:** Supabase Dashboard → Project Settings → API → service_role key
-- **⚠️ Critical:** Never expose this to the client. Used only in server-side code.
+#### `DATABASE_URL`
+Full Postgres connection string. The app uses this exclusively (no Supabase, no JS client) for every server-side query — server actions and API routes import a shared `pg` `Pool` from `src/lib/db.ts` and call `SECURITY DEFINER` PL/pgSQL functions.
+- **Where to get:** Neon Dashboard → Project → Connection Details → Connection string (pooled)
+- **Example:** `postgresql://user:pass@ep-xxx.us-east-2.aws.neon.tech/routecommerce?sslmode=require`
+- **Format:** `postgres://user:pass@host:port/dbname?sslmode=require`
+
+#### `DATABASE_ADMIN_URL` (optional)
+Same connection string but with elevated perms (typically the direct, non-pooled Neon connection). Only used by `scripts/migrate.js` for DDL — fall back to `DATABASE_URL` if unset.
 
 ### Stripe
 
@@ -168,7 +163,6 @@ Controls whether to use Square sandbox or production.
 - **Wrong Stripe key type:** Using `sk_live_` in development or `sk_test_` in production will silently fail. Always match key type to environment.
 - **Stripe price IDs drift:** If you create new prices in Stripe Dashboard but forget to update `.env.local`, billing will fail. Keep them in sync.
 - **SQUARE_ENVIRONMENT mismatch:** Production Square credentials won't work with `sandbox`. Match it to your app secret type.
-- **SUPABASE_SERVICE_ROLE_KEY in client:** If you ever see `SUPABASE_SERVICE_ROLE_KEY` in a browser bundle, it's a critical security incident. The key was exposed server-side. Rotate it immediately in Supabase Dashboard.
 - **OPENAI_API_KEY for AI features:** AI features won't work without this. The AI Intelligence Pack add-on requires a valid OpenAI key.
 
 ---