chat: hide panel immediately on submit, before awaiting handler
The TextInput submit callback was clearing text and sending
keyboard:close AFTER awaiting options.submitHandler. That's fine
when the default path's fire-and-forget client.server.send() runs
in microseconds, but for async submitHandlers like aa.mjs — which
awaits an entire SSE stream from Claude — the panel stayed open
for the whole reply. Move the clear/close up so UI feedback is
instant for both sync and async submit paths.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>