Remove legacy rename aliases

[corwinm]

Summary

• remove legacy opencode-tmux CLI, tmux entrypoint, plugin filename, env var, tmux option, state path, and Catppuccin aliases
• update docs and migration notes for the new-name-only release
• update tests to cover current coding-agents-tmux public surfaces only
• make tmux production bootstrap skip dev-only lifecycle scripts

Validation

• npm test
• npm run typecheck
• npm run lint
• npm run shell:check
• npm run fmt:check
• manual tmux plugin sync/reload verification