docs: refresh stale docs to match current implementation

Documentation pass — reviewed codebase in full, identified stale references,
and aligned docs with actual code state.

Changes:
- CLAUDE.md, PRODUCTION_SETUP.md, LAUNCH_CHECKLIST.md, src/auth.config.ts:
  middleware path src/middleware.ts → src/proxy.ts (Next.js 16+ convention)
- CLAUDE.md, ENVIRONMENT.md, README.md:
  dev server port localhost:3000 → localhost:4000 (per package.json dev
  script 'next dev --webpack -H 0.0.0.0 -p 4000')
- PRODUCTION_DEPLOYMENT_CHECKLIST.md:
  rewrote migration list — actual db/migrations/ contains 10 files
  (0000–0091), not the Supabase-era 001–092 series. Updated platform
  version 1.6 → 2.0 and last-updated stamp.
- MEMORY.md:
  refreshed 'Last updated' to 2026-06-25, added current-state header
  flagging Auth.js v5 wiring as historical, and documented the SSH/Gitea
  workflow (id_ed25519_crispygoat + no API token → push-hook URL flow
  for opening PRs).
- LAUNCH_CHECKLIST.md:
  added 'Last updated: 2026-06-25' header and refresh note in footer.
- CLAUDE.md:
  new 'Gitea authentication (SSH)' subsection under 'Canonical Remote'
  documenting ~/.ssh/id_ed25519_crispygoat, ssh-agent setup, what works
  (git push) vs what doesn't (REST API without token), and the actual
  PR-creation workflow (push + open the URL the Gitea hook prints).

Verification:
- npx tsc --noEmit: pre-existing Stripe API version + test mock errors
  only (verified by stashing changes and re-running — same error set).
- No new errors introduced.

ENVIRONMENT.md

@@ -12,7 +12,7 @@ These are safe to commit and can be used in client bundles. Prefix with `NEXT_PU
 
 ### `NEXT_PUBLIC_BASE_URL`
 The base URL of your deployment. Used for OAuth redirects and webhook URLs.
-- **Local:** `http://localhost:3000`
+- **Local:** `http://localhost:4000` (dev script binds to port 4000; override via `npm run dev -- -p <port>`)
 - **Production:** `https://yourdomain.com`
 
 ### `NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY`
@@ -151,7 +151,7 @@ Controls whether to use Square sandbox or production.
 
 | Variable | Local (`.env.local`) | Production (hosting dashboard) |
 |---|---|---|
-| `NEXT_PUBLIC_BASE_URL` | `http://localhost:3000` | `https://yourdomain.com` |
+| `NEXT_PUBLIC_BASE_URL` | `http://localhost:4000` (or whatever port the dev server is on) | `https://yourdomain.com` |
 | `STRIPE_SECRET_KEY` | `sk_test_...` | `sk_live_...` |
 | `STRIPE_PUBLISHABLE_KEY` | `pk_test_...` | `pk_live_...` |
 | `SQUARE_ENVIRONMENT` | `sandbox` | `production` |