Write a SpacetimeDB backend module in C# that defines a table of user profiles and a per-user view that returns only the calling user's profile.

TABLES
- Profile
  - Struct: Profile
  - Fields:
    - Id: ulong (primary key, AutoInc)
    - Identity: Identity (unique)
    - Name: string
    - Bio: string

VIEWS
- MyProfile
  - per-user view (uses ViewContext, not AnonymousViewContext)
  - public
  - Returns: Profile? (the single profile matching ctx.Sender, or null)
  - Logic: find the profile by the Identity column matching ctx.Sender
