Bootstrap automatically before running the delegate

[jezdez]

Summary

• bootstrap the managed prefix automatically on first use
• pass all command-line arguments to the configured delegate unchanged
• remove the conda-ship runtime command parser and conda-specific output rewriting
• stop setting conda activation variables while keeping managed-prefix executables on PATH
• add cs run --install-path and a runtime-specific _PREFIX override
• update docs, workflows, demos, and the bug report template for first-run bootstrap and direct delegate execution

Stamped binary templates, lock derivation, and the online, external, and embedded artifact layouts remain in place. The configured delegate can be conda, Python, or another executable.

This builds on the optional runtime package support merged in #66. The conda shell alias is handled separately by conda/conda-spawn#59.

Closes #63