Add an "I" button to the mobile shortcut bar that opens a chat-style
input box pinned above the virtual keyboard. Text is delivered to the
remote through the existing clipboard bridge (clipboard_set + synthetic
Ctrl+V); an empty box turns Enter/Backspace into remote Enter/Backspace
so the phone can submit and edit text in the focused window. The box
soft-wraps and auto-grows up to four lines.
The box is a <textarea>, so the desktop key-forwarding handlers now skip
TEXTAREA targets as well, which stops an empty-box Backspace from being
forwarded twice (once by imeBackspace, once by the document handler).
Co-Authored-By: deepseek-v4-pro
