Add full user management section (tab to Users):
- User list table with username, email, created date
- n: create user (username + email form)
- d: delete user with confirmation (cascades API keys)
- k: API key management for selected user
- n: create new key with name input; one-time reveal
showing key value and integer key ID prominently
- r: revoke by integer ID (no list endpoint on server)
- c: copy revealed key to clipboard (atotto/clipboard)
API key listing is unavailable server-side, so the reveal
screen displays the key ID prominently for future revocation.
Niklas Ye
9a50770538