ci: add install-only workflow for manual dependency install checks

[lucifer4330k]

Adds a small GitHub Actions workflow that can be manually dispatched (or triggered on PR) to run the project dependency installation step for Python 3.10 and 3.11. This helps maintainers re-run the pip resolver quickly to debug 'resolution-too-deep' issues without running the full CI matrix. Workflow: How to use: go to the Actions tab or the workflow on the PR and click 'Run workflow' (choose a python version) to re-run the dependency install.This PR targets the parent repo so CI can be re-run on the branch; it's safe and only installs packages (no tests or deployments).

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