fix: move email-in-address endpoint from /auth to /api/v1 prefix

The GET /me/email-in-address endpoint was unreachable because the Gateway
HTTPRoute routes all /auth/* traffic to Better-Auth (port 3001), not the
API service. This change:
- Moves the endpoint from the /auth router to a new /api/v1/me/ router
- Adds EmailInAddressResponse schema and get_email_in_address service method
- Updates Settings.tsx to call /api/v1/me/email-in-address

Fixes CAR-445.

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

src/cartsnitch_api/schemas.py

@@ -1,6 +1,7 @@
 """Pydantic v2 request/response schemas for all API endpoints."""
 
 from datetime import datetime
+from uuid import UUID
 
 from pydantic import BaseModel, EmailStr, Field
 
@@ -21,6 +22,10 @@ class UserResponse(BaseModel):
     created_at: datetime
 
 
+class EmailInAddressResponse(BaseModel):
+    email_address: str
+
+
 # ---------- Stores ----------