feat: 添加 USB 摄像头连接功能

- 新增 Android USB 摄像头 APP (MJPEG 服务器)
- 电脑端支持 ADB 端口转发连接
- 修复 .gitignore 忽略 Android 文件

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

android-app/app/build/intermediates/incremental/packageDebug/tmp/debug/dex-renamer-state.txt

@@ -0,0 +1,10 @@
+#Thu Feb 12 22:10:49 CST 2026
+base.0=D\:\\code\\post-ocr\\android-app\\app\\build\\intermediates\\dex\\debug\\mergeExtDexDebug\\classes.dex
+base.1=D\:\\code\\post-ocr\\android-app\\app\\build\\intermediates\\dex\\debug\\mergeProjectDexDebug\\0\\classes.dex
+base.2=D\:\\code\\post-ocr\\android-app\\app\\build\\intermediates\\dex\\debug\\mergeProjectDexDebug\\4\\classes.dex
+path.0=classes.dex
+path.1=0/classes.dex
+path.2=4/classes.dex
+renamed.0=classes.dex
+renamed.1=classes2.dex
+renamed.2=classes3.dex