fix: remove clipboard from HarmonyOS capabilities and correct test docs

- capabilities: remove harmonyos clipboard support because uitest uiInput
  has no getClipboard/setClipboard commands
- test docs: fix settings dark-mode → settings appearance dark
- test docs: fix fling → gesture fling with correct args

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: wangcz

src/core/capabilities.ts

@@ -126,11 +126,10 @@ const COMMAND_CAPABILITY_MATRIX: Record<string, CommandCapability> = {
   clipboard: {
     apple: { simulator: true, device: true },
     android: { emulator: true, device: true, unknown: true },
-    harmonyos: HARMONYOS_DEVICE,
+    harmonyos: {},
     linux: LINUX_DEVICE,
     supports: (device) =>
       device.platform === 'android' ||
-      device.platform === 'harmonyos' ||
       device.platform === 'linux' ||
       device.platform === 'macos' ||
       device.kind === 'simulator',