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>

test/kernel/src/panels/panel_resizer_kernel_test.dart

@@ -0,0 +1,58 @@
+/// Tests the kernel-side bridge that connects the Flutter-free
+/// `panel.resize` handler (T-119) to the live [LayoutArrangement].
+/// The handler-side tests live in
+/// `test/daemon/panel_commands_test.dart` against an in-memory fake.
+library;
+
+import 'package:clide/kernel/kernel.dart';
+import 'package:clide/src/daemon/panel_resizer_kernel.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('ArrangementPanelResizer', () {
+    late LayoutArrangement arrangement;
+    late ArrangementPanelResizer r;
+
+    setUp(() {
+      arrangement = LayoutArrangement()..applyPreset(classicPreset());
+      r = ArrangementPanelResizer(arrangement);
+    });
+
+    test('setSlotSize forwards to LayoutArrangement.setSize and clamps', () {
+      final ok = r.setSlotSize('sidebar', 10000);
+      expect(ok, isTrue);
+      expect(arrangement.sizeOf(Slots.sidebar), arrangement.maxSizeOf(Slots.sidebar));
+      expect(r.currentSlotSize('sidebar'), arrangement.sizeOf(Slots.sidebar));
+    });
+
+    test('setSlotSize returns false for an unknown slot', () {
+      expect(r.setSlotSize('does-not-exist', 250), isFalse);
+    });
+
+    test('bumpSlotSize applies the T-111 sign-flip on context panel', () {
+      final start = arrangement.sizeOf(Slots.contextPanel)!;
+      final ok = r.bumpSlotSize('context', 40);
+      expect(ok, isTrue);
+      // Context sits on the right edge — positive delta shrinks it.
+      expect(arrangement.sizeOf(Slots.contextPanel), lessThan(start));
+    });
+
+    test('bumpSlotSize returns false for an unknown slot', () {
+      expect(r.bumpSlotSize('nope', 5), isFalse);
+    });
+
+    test('setEditorRatio + currentEditorRatio round-trip through arrangement', () {
+      r.setEditorRatio(0.5);
+      expect(arrangement.editorRatio, 0.5);
+      expect(r.currentEditorRatio, 0.5);
+    });
+
+    test('bumpEditorRatio adds to current ratio (kernel re-clamps)', () {
+      r.setEditorRatio(0.4);
+      r.bumpEditorRatio(0.2);
+      expect(arrangement.editorRatio, closeTo(0.60, 1e-9));
+      r.bumpEditorRatio(1.0); // out-of-range; kernel clamps to 0.70
+      expect(arrangement.editorRatio, 0.70);
+    });
+  });
+}