feat(driver): add Android UiAutomator2 driver

Register `SUPPORTED_DRIVER_TYPES["uiautomator2"]` backed by the new
`AndroidDriver`, mirroring `WDADriver` method-for-method. tap/swipe/home use
the confirmed UiAutomator2 mobile commands (`clickGesture`, `dragGesture`,
`pressKey`); swipe converts `duration_ms` to a drag speed with a zero-distance
guard. Adds 34 mocked unit tests, an env-var-gated integration test, and
corrects the outdated "Android not registered" note in the iPhone setup doc.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_android_integration.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+import os
+
+import pytest
+
+from driver.android_driver import AndroidDriver, AndroidDriverConfig
+
+
+@pytest.mark.integration
+def test_android_driver_screenshot_against_real_device() -> None:
+    server_url = os.getenv("APEX_ANDROID_SERVER_URL")
+    if not server_url:
+        pytest.skip("set APEX_ANDROID_SERVER_URL to run Android hardware integration")
+
+    driver = AndroidDriver(
+        AndroidDriverConfig(
+            server_url=server_url,
+            udid=os.getenv("APEX_ANDROID_UDID") or None,
+            device_name=os.getenv("APEX_ANDROID_DEVICE_NAME") or None,
+        )
+    )
+    driver.connect()
+    try:
+        assert driver.screenshot()
+    finally:
+        driver.disconnect()