ClassCastException when declared remote dependency is resolved as local during `pkl package resolve`

Repro steps:

Check out this commit: https://github.com/rnapier/pkl-pantry/commit/ce6b87c0568636290bb86b624bcd137d367de511

Then bump version on `pkl.experimental.uri`, then run `pkl project resolve packages/*/`

Reproduce the failure from commit ce6b87c0568636290bb86b624bcd137d367de511 by bumping pkl.experimental.uri and running `pkl project resolve packages/*/`. Trace the package-resolution entry point for how a declared remote dependency becomes local, then verify that the command completes without a ClassCastException while resolving the dependency correctly.

Written by the indexing model from the issue text.