Move slot expansion logic to ExchangeService

- Add get_available_slots() and _expand_availability_to_slots() to ExchangeService
- Update routes/exchange.py to use ExchangeService.get_available_slots()
- Remove all business logic from get_available_slots endpoint
- Add AvailabilityRepository to ExchangeService dependencies
- Add Availability and BookableSlot imports to ExchangeService
- Fix import path for validate_date_in_range (use date_validation module)
- Remove unused user_repo variable and import from routes/invites.py
- Fix mypy error in ValidationError by adding proper type annotation

backend/services/profile.py

@@ -0,0 +1,82 @@
+"""Profile service for managing user profile details."""
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from exceptions import ValidationError
+from models import User
+from repositories.user import UserRepository
+from schemas import ProfileResponse, ProfileUpdate
+from validation import validate_profile_fields
+
+
+class ProfileService:
+    """Service for profile-related business logic."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+        self.user_repo = UserRepository(db)
+
+    async def get_profile(self, user: User) -> ProfileResponse:
+        """
+        Get user profile with godfather email.
+
+        Args:
+            user: The user to get profile for
+
+        Returns:
+            ProfileResponse with all profile fields and godfather email
+        """
+        godfather_email = await self.user_repo.get_godfather_email(user.godfather_id)
+
+        return ProfileResponse(
+            contact_email=user.contact_email,
+            telegram=user.telegram,
+            signal=user.signal,
+            nostr_npub=user.nostr_npub,
+            godfather_email=godfather_email,
+        )
+
+    async def update_profile(self, user: User, data: ProfileUpdate) -> ProfileResponse:
+        """
+        Validate and update profile fields.
+
+        Args:
+            user: The user to update
+            data: Profile update data
+
+        Returns:
+            ProfileResponse with updated fields
+
+        Raises:
+            ValidationError: If validation fails (with field_errors dict)
+        """
+        # Validate all fields
+        errors = validate_profile_fields(
+            contact_email=data.contact_email,
+            telegram=data.telegram,
+            signal=data.signal,
+            nostr_npub=data.nostr_npub,
+        )
+
+        if errors:
+            # Keep field_errors format for backward compatibility with frontend
+            raise ValidationError(message="Validation failed", field_errors=errors)
+
+        # Update fields
+        user.contact_email = data.contact_email
+        user.telegram = data.telegram
+        user.signal = data.signal
+        user.nostr_npub = data.nostr_npub
+
+        await self.db.commit()
+        await self.db.refresh(user)
+
+        godfather_email = await self.user_repo.get_godfather_email(user.godfather_id)
+
+        return ProfileResponse(
+            contact_email=user.contact_email,
+            telegram=user.telegram,
+            signal=user.signal,
+            nostr_npub=user.nostr_npub,
+            godfather_email=godfather_email,
+        )