fix: enable multiline paste in web terminal

Multiline pastes into the web terminal (especially into pi) were split
into one prompt per line because bracketed-paste markers were not
reaching the foreground app intact.

- Put the host PTY into raw mode (tty.setraw) after openpty() so it acts
  as a pass-through pipe. The default canonical line discipline was
  line-buffering input, splitting multiline pastes at newlines, and
  mangling bracketed-paste markers before docker exec / pi could see
  them. The in-container PTY (docker exec -t) provides real discipline.
- Route the mobile Paste button through xterm.js (term.paste) instead of
  sending raw clipboard text to the WebSocket, so content is wrapped in
  bracketed-paste markers when the app has enabled BPM.
- Treat a text frame as a control message only when it is a JSON object
  with a known type (resize/ack/reset); otherwise forward as raw input
  so JSON-shaped pastes are no longer silently dropped.

Quality gates: ruff, mypy (changed files), pytest unit (227 passed),
tsc, eslint

apps/web/src/components/features/terminal/terminal.tsx

@@ -722,9 +722,13 @@ export const TerminalComponent = React.forwardRef<TerminalRef, TerminalProps>(
     const handlePaste = async () => {
       try {
         const text = await navigator.clipboard.readText();
-        if (wsRef.current?.readyState === WebSocket.OPEN) {
-          wsRef.current.send(text);
-        }
+        // Route through xterm.js instead of sending raw text directly.
+        // term.paste() wraps the content in bracketed-paste markers
+        // (\e[200~...\e[201~) when the app has enabled BPM, so multiline
+        // pastes arrive as a single input rather than one prompt per line.
+        // It emits via onData, which the existing handler forwards to the
+        // WebSocket, so the readyState check happens there.
+        termRef.current?.paste(text);
       } catch {
         // Clipboard API not available
       }