android: build.sh installs and syncs the game files when a phone is attached

After building the APK, android/build.sh now picks the attached device (ANDROID_SERIAL for several),
installs the APK (reinstalling on a signature mismatch), syncs the zh client into files/Client and, with
--launch, wakes the phone and starts the app. Without a device it only builds.

push-client.sh is now incremental (android/sync_client.py): the device keeps files/Client/.mt_sync
(size, mtime, path of what the last sync wrote), so later syncs send only new and changed files as one
tar streamed through `adb shell -T run-as` (no copy in /data/local/tmp) and delete the ones gone
locally. Only game resources are synced; settings and logs the app writes there are kept. --locale zh
rebuilds build/zh-locale/Client first when its inputs changed. android/adb_env.sh picks adb and falls
back to server port 5038 when :5037 cannot bind.

Verified against a fake adb device: first sync (1.4 GB, byte-identical), no-op resync, changed files,
deletions, locale switch, --full, the install/launch path and the no-device path.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/ZH-LOCALE.md

@@ -34,7 +34,7 @@ build/native/src/host/mt_native_render \
   --live-client build/zh-locale/Client --login-screen --width 1024 --height 768
 ```
 
-Android：`./android/push-client.sh --locale zh`（默认推送 `build/zh-locale/Client`，符号链接按
+Android：`./android/build.sh` 连着手机时自动执行 `./android/push-client.sh --locale zh`（默认推送 `build/zh-locale/Client`，输入变化时先重新生成，符号链接按
 目标文件复制，并以 `locale_zh.cfg` 写入设备上的 `locale.cfg`）。
 
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