Add project path paste and safe terminal link opening

[TroopJostle]

Summary

• Add clipboard paste support to the agent launcher for project folder paths, including local path and file URI handling.
• Add a chooser for terminal HTTP(S) links so users can open them in the embedded Canvas browser or the system browser.

Security

• Clipboard access crosses the trusted IPC boundary.
• Terminal links are validated as HTTP(S)-only before either open action.

Validation

• Node and web TypeScript checks passed.
• Focused tests: 3/3 passed.
• Full test suite: 538/538 passed.

[TroopJostle]

Superseded by #27 (project-path clipboard paste) and #28 (terminal link chooser), split into independent changes as requested.