Guidance requested: integrated Alembic migration CLI dependencies

[vmskonakanchi]

Hi maintainers,

I revived the work from #689 against current main in #2061. The implementation adds a sqlmodel migrations CLI with Alembic commands and documentation. The test matrix passed, but #2061 was closed automatically because it modifies pyproject.toml and uv.lock.

The feature needs Alembic and Typer available at runtime for the console command. Before proposing it again, could you advise which packaging direction you prefer?

1. Make Alembic and Typer core runtime dependencies.
2. Expose the migration CLI through an optional dependency extra.
3. Keep migrations as documented integration/template guidance rather than a SQLModel CLI.

The updated implementation preserves the current PDM/uv setup and current CI, and replaces the original deprecated entry-point loader with importlib.metadata. I am happy to adapt the PR to the preferred design.

Thanks!