Add place notes field to photos

[Copilot]

This adds a dedicated notes field to photos for place-specific context, separate from the existing photo description. The backend now stores, accepts, and returns notes explicitly, while keeping room for future annotation-style editing/licensing mechanics.

• Schema

  • Add nullable notes column to photos
  • Include Alembic migration for the new field

• Upload + persistence

  • Accept notes in the upload authorization request
  • Persist notes onto the Photo model alongside existing metadata

• API surface

  • Return notes from photo-facing endpoints that already expose photo metadata
  • Omit empty notes values from responses for consistency with existing optional fields

• Content selection logic

  • Treat notes as meaningful photo metadata in places that decide whether a photo is “contentful” enough for sitemap/place flows

• Focused test coverage

  • Add unit coverage for request parsing and response serialization of notes

class UploadAuthorizationRequest(BaseModel):
    title: Optional[str] = None
    description: Optional[str] = None
    notes: Optional[str] = None
    keywords: Optional[list[str]] = None