Converts hardcoded UI copy to i18n keys across the app, adds global translation for non-component modules, and splits the English catalog into feature modules with duplicate-key detection.
Cmd+Shift+[ and Cmd+Shift+] now cycle through visible sessions only (parents + expanded children) and no longer include Instance Info. Sidebar session list auto-scrolls to keep the active session row in view.
Show sessions as parent/child threads with expand/collapse and improved agent row styling. Keep a 5-session cache to avoid refetching messages when switching between recently visited sessions.
- make the blank session cleanup system optionally fetch full message histories for each session to better judge if it's blank
- make a command that does the deep clean, keep the clean that happens on new session creation shallow
