fix(api): revert auth/type regressions from standalone sync, keep email-in feature only

- Revert auth/dependencies.py to cookie+Bearer dual auth with str user IDs
- Add GET /auth/me/email-in-address endpoint for receipt email routing
- Update User model: add email_inbound_token, change id/store_id/user_id to str
- Update AuthService and UserResponse to use str user IDs
- Update route count test: 33 -> 34 routes
- Restore e2e test for email-in-address endpoint

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/cartsnitch_api/config.py

@@ -19,6 +19,8 @@ class Settings(BaseSettings):
     # Valid Fernet key for local dev — MUST be overridden in production
     fernet_key: str = "7reF42nmTwbdN21PBoubGp7h_FU8qSimstmlaMLoRK8="
 
+    auth_service_url: str = "http://auth:3001"
+
     cors_origins: list[str] = ["http://localhost:3000", "https://cartsnitch.com"]
 
     receiptwitness_url: str = "http://receiptwitness:8001"