mcp(fix[pane_tools]): Query tmux for zoom state instead of missing attr

why: `getattr(window, "window_zoomed_flag", "0")` always returned the
default `"0"` because `window_zoomed_flag` is not a field on libtmux's
`Window` object. This caused `zoom=True` on an already-zoomed pane to
toggle it OFF (since `pane.resize(zoom=True)` is a toggle), and
`zoom=False` on a zoomed pane to be a no-op.
what:
- Query zoom state via `window.cmd("display-message", "-p", "#{window_zoomed_flag}")`
- Preserve idempotent semantics: zoom=True ensures zoomed, zoom=False ensures unzoomed

Author: tony

src/libtmux/mcp/tools/pane_tools.py

@@ -160,7 +160,8 @@ def resize_pane(
     )
     if zoom is not None:
         window = pane.window
-        is_zoomed = getattr(window, "window_zoomed_flag", "0") == "1"
+        result = window.cmd("display-message", "-p", "#{window_zoomed_flag}")
+        is_zoomed = bool(result.stdout) and result.stdout[0] == "1"
         if zoom and not is_zoomed:
             pane.resize(zoom=True)
         elif not zoom and is_zoomed: