Add \oh-my-posh copilot\ command that reads GitHub Copilot CLI session
JSON from stdin and renders a statusline prompt.
- New copilot_cli segment with token gauge, model, cost, and context
window template properties
- Shared statuslineRun[T] pipeline in cli/statusline.go eliminates
boilerplate between claude and copilot commands
- Extract AIModel, formatTokenCount, and statuslineCLIConfig helpers
to reduce duplication across the two segments
- Add CLAUDE/COPILOTCLI shell constants and CLAUDECACHE/COPILOTCLICACHE
cache key constants
- Fix: ignore POSH_CONFIG env var in statusline commands so the
built-in default config is used unless --config is explicitly passed
- Adjust terminal width for copilot-cli shell (4-char frame padding)
- Add copilot tab to prompt.mdx installation docs
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
