fix(remote): reset SGR at the remote scrollback splice seam (#602 merge-time fix)

joinScrollbackAndFrame joins two separate `capture-pane -e` outputs. The
remote history's last row can end with attributes still active (a diff row's
background, dim tool output), while the local frame is encoded relative to
the default state, so its first plain rows inherited them in the browser. A
`\x1b[0m` now ends the scrollback before the frame.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/tmux-manager.ts

@@ -701,7 +701,9 @@ export function normalizeScrollbackEol(buffer: string): string {
  */
 export function joinScrollbackAndFrame(scrollback: string | undefined, frame: string): string {
   if (!scrollback) return frame;
-  return `${scrollback.replace(/\n$/, '')}\n${frame}`;
+  // Two separate captures: tmux encodes the frame relative to the DEFAULT
+  // state, so the scrollback's last row must not leave its attributes active.
+  return `${scrollback.replace(/\n$/, '')}\x1b[0m\n${frame}`;
 }
 
 /** Pane geometry and caret position, as `display-message` reports them. */