v0.2.0

First correctly-versioned PyPI release (earlier tags all published as 0.1.0 due to a static version in the build).

Highlights since 0.1.0:

• Removed persistent container mode and the container_mode option; container runs always use a fresh, auto-removed container (breaking change).
• Session workspaces now live under <home>/sessions/<id>; RUNSPACE_DATA_DIR sets the home (defaults to {tmp}/runspace).
• Server port configurable via RUNSPACE_PORT; python -m runspace_agent works as an alias for runspace-srv.
• Session UI shows the execution mode; agent-agnostic credential docs (pass creds via agent_settings.env).
• Shared build_claude_env helper for examples/tests.
• Publish workflow now derives the version from the release tag.