[Bug] Fullscreen TUI mode breaks clipboard and mouse text selection without visible escape hatch

Bug Description
The new fullscreen TUI mode (tui: "fullscreen", 2.1.191) broke my
workflow. After accepting the opt-in prompt, I lost mouse text
selection and couldn't copy/paste between CLI windows — the
alt-screen mode captures the mouse and overrides my terminal's
native selection. Shift+Ctrl+C is labeled "copy" but only copies
internally; it never reached my system clipboard.

I had to dig into settings.json and set tui: "default" to get my
workflow back. That shouldn't require editing a config file.

Three asks:

1. Make Shift+Ctrl+C write to the system clipboard (OSC 52), not

just an internal buffer.

1. Show a visible hint that Shift+drag does a native selection

when the mouse is captured — nobody knows that bypass exists.

1. Give an obvious in-session toggle back to default instead of a

buried /config path.

Fullscreen is genuinely nicer for redraw/flicker, but capturing
the mouse with no escape hatch is a hard break for anyone who
copies text out of the terminal.

Environment Info

• Platform: linux
• Terminal: gnome-terminal
• Version: 2.1.191
• Feedback ID: 04a1f516-fa52-40d0-9862-f1ba20e7435c

Errors

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