skill: add Android skills

.agents/skills/camerax/references/expert-blueprints.md

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+Complex camera features often fail due to "Agent Stall" or timeouts when
+attempted in a single turn. Use these blueprints to break tasks into manageable
+phases.
+
+## Manual controls
+
+### Phase one: ViewModel and state
+
+1. Define a `ManualSettings` data class.
+2. Add a `MutableStateFlow<ManualSettings>` to your `CameraViewModel`.
+3. Implement the Jetpack Compose UI with sliders and switches to update this flow.
+
+### Phase two: Controller wiring
+
+1. In `CameraController.kt`, create a new function `updateManualSettings(settings: ManualSettings)`.
+2. Map these settings into the `CameraSystem` layer.
+
+### Phase three: CameraX `Camera2Interop` wiring
+
+1. In `CameraSession.kt`, use the `Camera2Interop.Extender` utility to access Camera2 capture request keys.
+2. Apply the hardware keys:
+   - `CaptureRequest.SENSOR_SENSITIVITY` to set ISO sensitivity.
+   - `CaptureRequest.SENSOR_EXPOSURE_TIME` to set exposure time.
+   - `CaptureRequest.LENS_FOCUS_DISTANCE` to set focus distance.
+3. **Critical** : If manual exposure is active, set `CaptureRequest.CONTROL_AE_MODE` to `CameraMetadata.CONTROL_AE_MODE_OFF`. ---
+
+## RAW and JPEG capture
+
+### Phase one: Output configuration
+
+1. Verify device support for RAW capture using `CameraInfo`.
+2. Configure `ImageCapture.Builder` with `OUTPUT_FORMAT_RAW_JPEG` or `OUTPUT_FORMAT_RAW`.
+
+### Phase two: Implementation
+
+1. Provide `ImageCapture.OutputFileOptions` for the target storage locations.
+2. Invoke `takePicture`. CameraX internally manages `DngCreator` to wrap RAW data with the required `CameraCharacteristics` and `CaptureResult` metadata.
+
+*** ** * ** ***
+
+## Apply image effects
+
+### Phase one: Effects selection
+
+1. Use the `androidx.media3:media3-effect` dependency.
+2. Use `RgbFilter` or `HslAdjustment` for standard color grading.
+
+### Phase two: Application
+
+1. Configure `Composition.Builder` or `MediaItem.Builder` with the list of effects.
+2. Inject the list of effects into the CameraX `Recorder` or `Preview` using the `setEffects` method.
+
+*** ** * ** ***
+
+## Low-light capture
+
+For guidance on Night Mode Extensions and Low Light Boost,
+[low-light.md](https://developer.android.com/agents/skills/camera/camerax/references/low-light).