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

stream.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+"""Auto-detect and start the best available streamer."""
+
+import importlib.util
+import subprocess
+import sys
+
+
+def main():
+    # Check if picamera2 is available and a Pi camera is connected
+    if importlib.util.find_spec("picamera2") is not None:
+        try:
+            from picamera2 import Picamera2
+
+            # Attempt to create a camera to see if hardware is present
+            cam = Picamera2()
+            cam.close()
+            print("Detected Raspberry Pi camera. Starting picamera2 streamer...")
+            subprocess.run([sys.executable, "stream_picamera2.py"] + sys.argv[1:])
+            return
+        except Exception as e:
+            print(f"picamera2 available but camera not detected ({e}).")
+    else:
+        print("picamera2 not installed.")
+
+    # Fall back to USB / OpenCV
+    print("Falling back to USB camera streamer...")
+    subprocess.run([sys.executable, "stream_usb.py"] + sys.argv[1:])
+
+
+if __name__ == "__main__":
+    main()