Sync pyte screen to actual PTY size before screenshots

Query PTY size with TIOCGWINSZ and resize pyte screen to match.
Fixes tmux status bar wrapping when terminal was resized externally.

src/textual_webterm/terminal_session.py

@@ -105,6 +105,27 @@ class TerminalSession(Session):
         assert self.master_fd is not None
         fcntl.ioctl(self.master_fd, termios.TIOCSWINSZ, buf)
 
+    def _get_terminal_size(self) -> tuple[int, int]:
+        """Get actual PTY size. Returns (width, height)."""
+        assert self.master_fd is not None
+        buf = array.array("h", [0, 0, 0, 0])
+        fcntl.ioctl(self.master_fd, termios.TIOCGWINSZ, buf)
+        return (buf[1], buf[0])  # cols, rows
+
+    async def _sync_pyte_to_pty(self) -> None:
+        """Sync pyte screen size to actual PTY size."""
+        if self.master_fd is None:
+            return
+        loop = asyncio.get_running_loop()
+        width, height = await loop.run_in_executor(None, self._get_terminal_size)
+        async with self._screen_lock:
+            if self._screen.columns != width or self._screen.lines != height:
+                log.debug("Syncing pyte screen from %dx%d to %dx%d",
+                         self._screen.columns, self._screen.lines, width, height)
+                self._screen.resize(height, width)
+                self._last_width = width
+                self._last_height = height
+
     async def set_terminal_size(self, width: int, height: int) -> None:
         # Track the size for reconnection
         self._last_width = width
@@ -174,6 +195,9 @@ class TerminalSession(Session):
             - buffer: list of rows, each containing character data with styling
             - has_changes: True if screen has changed since last call
         """
+        # Sync pyte to actual PTY size before reading state
+        await self._sync_pyte_to_pty()
+
         async with self._screen_lock:
             width = self._screen.columns
             height = self._screen.lines