feat: add pi coding-agent integration

[cat0825]

Summary

Adds first-class support for pi (@earendil-works/pi-coding-agent) and Oh My Pi / OMP (@oh-my-pi/pi-coding-agent) by installing bundled TypeScript extensions into their global extension directories.

Fixes #196.

What changed

• Adds pi to the built-in CLI list as a .none installer target.
• Adds Oh My Pi / OMP to the built-in CLI list as a .none installer target.
• Installs Sources/CodeIsland/Resources/codeisland-pi.ts to ~/.pi/agent/extensions/codeisland.ts when ~/.pi/agent exists.
• Installs Sources/CodeIsland/Resources/codeisland-omp.ts to ~/.omp/agent/extensions/codeisland.ts when ~/.omp/agent exists.
• Wires pi and OMP status, enable/disable, uninstall, and repair paths through ConfigInstaller.
• Updates the pi extension to current package names:
  • @earendil-works/pi-coding-agent
  • @earendil-works/pi-ai
• Adds an OMP-specific extension using:
  • @oh-my-pi/pi-coding-agent
• Tags the extensions with a version marker so repair can detect stale installs.
• Uses session_title for completion events, matching CodeIsland's session title metadata field.
• Adds installer tests for install, missing agent dir no-op, uninstall safety, and stale-version detection.

Verification

• swift test --filter ConfigInstallerTests
• Typechecked codeisland-pi.ts against a local @earendil-works/pi-coding-agent checkout.
• Typechecked codeisland-omp.ts against a local @oh-my-pi/pi-coding-agent install.
• Locally smoke-tested omp-pi -e ~/.omp/agent/extensions/codeisland.ts ... and verified CodeIsland recorded a live source: "pi" session with Ghostty terminal metadata.