v0.9.0

v0.9.0 — Agent-to-agent file transfer + cross-platform fixes

New features:
- Agent-to-agent file transfer via hub relay (chunked, SHA-256 verified)
  - orchestratia file send <path> --to <session-name>
  - orchestratia file status <transfer-id>
  - 64KB chunks, zero hub disk storage, same-project+same-owner access control

Bug fixes:
- Fix 404 on Windows: strip trailing slash from hub_url in CLI
- Fix orchestratia update on Windows: re-run PowerShell installer in upgrade mode
- Fix orchestratia update on macOS: use pip install --upgrade (no git repo)
- Fix macOS log path: use ~/Library/Logs/Orchestratia (was using Linux path)
- Fix uninstall.sh: check both user and system launchd plist locations

Improvements:
- PyInstaller spec: add tunnel, file_transfer, connect, virtual_screen
- SKILL.md: add file transfer documentation
- ORCHESTRATIA.md template: add remote exec and file transfer docs
- Platform-aware restart hints in update command output