- Remove user=="git" restriction from auth_password: the actual user is
determined by the token, not the SSH username, matching Gitea's approach
- Add channel_open_session logging with explicit flush to verify
CHANNEL_OPEN_CONFIRMATION reaches the client
- Add pty_request handler (reject with log) so git clients that request
a PTY are handled gracefully instead of falling through to default
- Add subsystem_request handler (log + accept) so git subsystems are
visible in logs
- Prefix unused variables with _ to eliminate warnings
1090359951