feat(native-export): scaffold local Expo module + native decode/encode bench probe (P0)

Local Kotlin module modules/recipescam-export (autolinked via expo ./modules)
exposes decodeEncodeAsync — BitmapFactory decode -> JPEG q95 encode -> file,
all on Dispatchers.IO off the JS/main threads. EXPO_PUBLIC_BENCH=1 builds run
src/dev/nativeBenchProbe.ts: 3 timed decode+encode passes on the bundled
wallframe artwork plus a JS-timer gap check proving the JS thread never
blocks during native rendering. Legacy Skia engine untouched (reference).

modules/recipescam-export/android/build.gradle

@@ -0,0 +1,15 @@
+plugins {
+  id 'com.android.library'
+  id 'expo-module-gradle-plugin'
+}
+
+group = 'com.locphamtran.recipescamera'
+version = '0.1.0'
+
+android {
+  namespace "com.locphamtran.recipescamera.export"
+  defaultConfig {
+    versionCode 1
+    versionName "0.1.0"
+  }
+}