UI operations from chat (open, tabs, folders, search, language)

Chat can also drive the UI (without changing any files):

• Open a note / tabs:"Open X", "Close this tab", "Close all tabs", "Switch to the Y tab". Asking "Open the X section (heading) of note Y" opens that note and scrolls to the heading.
• Expand/collapse folders:"Expand/collapse the X folder", "Expand/collapse all". This applies to both the sidebar and the gallery's folder-grouped view.
• Sorting:"Sort by most recently updated", "Sort by title".
• Search:"Find notes containing X" — opens the search panel with matching notes.
• Switch language:"Switch to English" — changes the UI display language (ja / en).
• Rebuild search index:"Search results look out of date", "Rebuild the index" — rebuilds the index without changing notes.