add panel.resize CLI verb (T-119)

The keyboard half of panel resizing landed in T-111 (arrow-key
splitters); this completes D-6 user/Claude parity with a CLI verb now
that T-99's IPC dispatch path exists. `clide panel resize <slot> --to N`
sets an absolute pixel size, `--by N` nudges relative to current, and
the reserved `editor` slot drives the editor/bottom-panel split ratio.

The handler lives in panel_commands.dart and stays Flutter-free (so
test/daemon/ keeps running under `dart test`) by talking to an abstract
PanelResizer; the kernel bridge in panel_resizer_kernel.dart wraps
LayoutArrangement and reuses T-111's bumpedSlotSize so the CLI's
relative deltas honour the same right-edge sign-flip as the drag/arrow
handlers. Arguments are lifted from both the direct call shape and the
argv-translator's positional/flags shape pending the typed schema in
T-120. The daemonClientFactory now receives the LayoutArrangement so
the dispatcher can reach it.

Co-Authored-By: Claude <noreply@anthropic.com>

integration_test/extension_lifecycle_test.dart

@@ -40,7 +40,7 @@ void main() {
         'builtin.ipc-status',
         'builtin.default-layout',
       ],
-      daemonClientFactory: (log, events) => FakeDaemonClient(log: log, events: events),
+      daemonClientFactory: (log, events, _) => FakeDaemonClient(log: log, events: events),
       autoStartDaemonClient: false,
     );
     services.extensions