feat: Implement server-managed camera settings with new API endpoints, client-side application, and updated documentation.

demo/README.md

@@ -76,6 +76,58 @@ VIDEO_DEVICE="/dev/video0"
 ./capture-upload.sh
 ```
 
+---
+
+## Camera Settings (Focus & Exposure)
+
+Camera settings are stored on the PicUpper server and applied before each capture.
+
+### Set camera settings via API
+
+```bash
+# Set focus and exposure for your camera
+curl -X PUT \
+  -H "X-API-Key: your-api-key" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "focus_automatic_continuous": 0,
+    "focus_absolute": 30,
+    "exposure_auto": 1,
+    "exposure_absolute": 200,
+    "brightness": 0,
+    "contrast": 32
+  }' \
+  https://dev.seedheads.de/picUploadApi/settings/rpi-webcam-1
+```
+
+### Get current settings
+
+```bash
+curl -H "X-API-Key: your-api-key" \
+  https://dev.seedheads.de/picUploadApi/settings/rpi-webcam-1
+```
+
+### Available settings (for Logitech C922)
+
+| Setting | Range | Description |
+|---------|-------|-------------|
+| `focus_automatic_continuous` | 0-1 | 0=manual, 1=auto |
+| `focus_absolute` | 0-255 | Lower=closer (manual mode) |
+| `exposure_auto` | 1-3 | 1=manual, 3=auto |
+| `exposure_absolute` | 3-2047 | Shutter speed (manual mode) |
+| `brightness` | -64 to 64 | Image brightness |
+| `contrast` | 0-64 | Image contrast |
+
+### Find your camera's available controls
+
+```bash
+v4l2-ctl -d /dev/video0 --list-ctrls
+```
+
+**Note:** Install `v4l-utils` on the Pi: `sudo apt install v4l-utils`
+
+---
+
 ## Troubleshooting
 
 ### Check if webcam is detected