[codex] Fix translation popup interaction

[tyreseluo]

Summary

• hide the room input realtime translation button when translation is disabled in settings
• close stale translation UI state automatically when the translation feature is turned off
• fix the room translation language popup so it can be dismissed by clicking outside and no longer leaks interaction to the timeline behind it

Why

The translation entry point was still visible even when the feature was disabled, and the language picker popup had broken interaction behavior. Scrolling could move the room timeline behind the popup, and the popup could trap the rest of the room UI until a language was chosen.

Impact

Users now only see the realtime translation control when the feature is enabled, and the language picker behaves like a normal modal: it accepts clicks and scrolling itself, blocks background interaction, and closes when clicking outside.

Root Cause

The room input bar did not sync the translation button visibility with the persisted translation config. The room screen also did not treat the translation language modal as the active interactive layer, so popup and background events were not isolated correctly.

Validation

• cargo build
• manual user verification of the translation button visibility and language popup behavior