feat(android): add screenshotStrategy option to force yadb screenshots

[quanruzhuoxiu]

Summary

This PR adds a new screenshotStrategy Android device option ('auto' | 'always-yadb') that lets users default to yadb-based screenshots. This is useful for capturing FLAG_SECURE pages (e.g. password entry screens in banking/payment apps) that screencap renders as black frames.

Why

When screencap captures a FLAG_SECURE page, the secure region appears black. The yadb tool creates a virtual display via the secure parameter of SurfaceControl.createDisplay, which can capture secure content directly on Android 11 and below (and on Android 12+ with root + Magisk hook). Users needed a way to force yadb screenshots instead of relying on the default fallback chain.

What

• core/android: implement screenshotBase64ViaYadb() and strategy check in screenshotBase64(); add MIDSCENE_ANDROID_SCREENSHOT_STRATEGY env var
• cli: document --android.screenshot-strategy in help text
• visualizer: wire screenshotStrategy through store (with localStorage persistence), config selector UI, and playground execution — mirroring the existing imeStrategy integration
• site: document screenshotStrategy in en/zh Android and reference docs
• tests: add unit tests for device option types, CLI arg parsing, and visualizer device capabilities / execution mocks

Usage

const device = new AndroidDevice('device-id', {
  screenshotStrategy: 'always-yadb',
});

YAML:

android:
  screenshotStrategy: always-yadb

Env var:

export MIDSCENE_ANDROID_SCREENSHOT_STRATEGY=always-yadb

The default is auto, which tries scrcpy → adb.takeScreenshot → screencap → yadb in order. always-yadb skips the earlier paths. Note yadb can only capture the default display (displayId=0).

Validation

• pnpm run lint (biome clean)
• npx nx test @midscene/core — 1385 passed, 8 skipped
• npx nx test @midscene/android — 352 passed
• npx nx test @midscene/cli — 203 passed
• npx nx test @midscene/visualizer — 109 passed
• npx nx build @midscene/visualizer — success

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