Add key pin controls to the TLD dashboard

[phucnguyen1707]

Summary

• list published TLS and MTP pins for each owned TLD
• publish rotation keys with an optional note
• withdraw old keys with confirmation and refresh the list in place
• explain how redirected TLDs use the target TLD pins

This brings the key-pin API added in #82 into the existing TLD dashboard, so operators no longer need curl for key rotation.

Testing

• bun test tests/moshpit-pins.test.mjs
• bun test tests/
• bunx tsc --noEmit
• bun run build