This commit implements project-aware functionality for the `cabal gen-bounds` command,
allowing it to work correctly in multi-package projects. Previously, running `gen-bounds`
from within a package directory that depends on another local package would fail
because it couldn't find the local dependency.

The implementation follows the same pattern as other v2 commands, creating a full
project context that knows about all packages defined in the cabal.project file.
This allows `gen-bounds` to properly analyze dependencies between local packages
and suggest appropriate bounds.

```
cabal gen-bounds <TARGET>
```

Fixes #7504 #8654 #9752 #5932