Add PiCam network streamer with auto-setup for Pi 5

Initial commit of the MJPEG streaming server for Raspberry Pi.
Supports Pi Camera Module (via picamera2), USB webcams (via OpenCV),
and auto-detection of camera type.

Includes:
- `stream_picamera2.py` — optimized Pi CSI camera streamer
- `stream_usb.py` — generic USB camera streamer
- `stream.py` — auto-detects camera and launches correct streamer
- `image-setup/` — SD card imaging scripts and Pi 5 headless setup
  guide for first-boot automation with systemd service
- `requirements.txt` — Python dependencies

image-setup/config_camera.txt

@@ -0,0 +1,11 @@
+# Add these lines to the end of your /boot/firmware/config.txt (or /boot/config.txt)
+# to explicitly enable the IMX219 camera module on Raspberry Pi 5.
+
+# IMX219 Camera Module v2
+dtoverlay=imx219
+
+# Ensure camera is enabled (legacy, usually not needed on Bookworm but safe)
+camera_auto_detect=1
+
+# Optional: Increase GPU memory if needed for higher resolutions
+# gpu_mem=128