chore: replace TurboStarter brand references in env templates + docs

- PRODUCT_NAME default: TurboStarter → claudemesh (.env.example, .env.local)
- SEED_EMAIL default: me@turbostarter.dev → dev@example.com
- README dev accounts table: reflect new seed email format
- DEPLOY.md: fix stale SEED_EMAIL reference

Keeps DB user as turbostarter per docker-compose.yml default; retains
TurboStarter attribution link in README Contributing section (legit
credit for the template this repo is built on).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.env.production.example

@@ -30,7 +30,7 @@ BETTER_AUTH_TRUSTED_ORIGINS="https://your-app.example.com"
 
 # ── PRODUCT ──────────────────────────────────────────────────
 
-# [OPTIONAL] App display name (default: "TurboStarter")
+# [OPTIONAL] App display name (default: "claudemesh")
 NEXT_PUBLIC_PRODUCT_NAME="MyApp"
 
 # [OPTIONAL] Contact email shown in the app