fix(uv): support virtual members and more uv_build build backend configuration options

[danielgafni]

No description provided.

[aoright]

Verified the changes across virtual workspace resolution and module layouts:

• Workspace resolution: Local package discovery now properly includes virtual workspace roots and virtual packages (tool.uv.package = false or missing build-system), ensuring transitive dependency resolution (find_transitive_local_deps) can traverse through virtual intermediate packages down to editable dependencies.
• Build plan: Staging accurately treats packages with package = false as dependency-only containers, preserving pyproject.toml for lock resolution while preventing spurious source staging.
• Layout support: The added module_paths property correctly accounts for [tool.uv.build-backend] custom module roots and names, ensuring compatibility with renamed and custom package structures.
• Dependency audit: Patched anyio (4.14.2) across workspace lockfiles satisfies vulnerability audits.

All 14 CI checks (dagger pipeline, deptry, ruff lint/format, uv:audit, zizmor) pass cleanly.

[danielgafni]

@aoright please do not spam here, I can manage it myself, thanks