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>

README.md

@@ -196,8 +196,8 @@ After `pnpm services:setup`:
 
 | Role  | Email                         | Password   |
 |-------|-------------------------------|------------|
-| User  | `me+user@turbostarter.dev`    | `Pa$$w0rd` |
-| Admin | `me+admin@turbostarter.dev`   | `Pa$$w0rd` |
+| User  | `dev+user@example.com`        | `Pa$$w0rd` |
+| Admin | `dev+admin@example.com`       | `Pa$$w0rd` |
 
 ### Common commands