fix: allow offline OCP version override

[butler54]

Summary

• support OCP_VERSION when bare-metal reference values are collected without an authenticated cluster
• standardize Python entry points on Typer for CLI parsing and Rich for console output
• centralize Python dependencies in root requirements.txt; RHDP wrappers install it with their selected Python 3.10+ interpreter
• document the connected staging-host workflow, root dependency installation, and airgap Git server prerequisites
• add pytest CLI smoke tests

Validation

• pytest -q
• python3 -m py_compile scripts/collect_firmware_refvals.py scripts/git-http-server.py rhdp/rhdp-cluster-define.py
• targeted OCP_VERSION and --ocp-version precedence checks
• bash -n rhdp/wrapper.sh rhdp/wrapper-multicluster.sh rhdp/wrapper-cluster-only.sh
• python3 -m pip install --dry-run -r requirements.txt
• python3 -m pip check
• git diff --check

Closes #147