Python bytecode precompilation forced; builds use in-repo source

Patch Changes

• 4637f0a: Force Python bytecode precompilation to rewrite existing .pyc files with unchecked-hash invalidation.
• c5d53d7: Use the in-repo python/vercel-runtime and python/vercel-workers source as the install target during monorepo vercel build runs (mirroring the existing dev-server behavior). This prevents CLI unit tests from depending on a PyPI release of a version that has not been published yet — the case that breaks Version Packages PRs that bump these packages.