Increase OAuth connection URL column lengths to 2048 characters

[Copilot]

OAuth providers (e.g. Google, GitHub) can return image_url and profile_url values exceeding 512 characters, causing truncation or insertion errors against the current Unicode(512) column constraint.

Changes

• model.py — Increase the length limit of profile_url and image_url on OauthConnection from 512 to 2048:

  # before
  profile_url: Mapped[str | None] = mapped_column(Unicode(512))
  image_url:   Mapped[str | None] = mapped_column(Unicode(512))
  
  # after
  profile_url: Mapped[str | None] = mapped_column(Unicode(2048))
  image_url:   Mapped[str | None] = mapped_column(Unicode(2048))

• alembic/versions/d3e4f5a6b7c8_expand_oauth_url_columns.py — New migration that ALTER COLUMNs both fields from VARCHAR(512) to VARCHAR(2048). The existing 5be3d628dcc3 migration is left untouched to avoid breaking already-applied environments.

[exhuma]

@copilot let's not make that an inbound limit. Set it to 2048

[Copilot]

@copilot let's not make that an inbound limit. Set it to 2048

Done — both profile_url and image_url are now Unicode(2048) in model.py and the migration (3bad043).