Fix hardcoded path bug + add CI for the hardware-independent surface

[Scottcjn]

Bug fix

camera/test_blur.py wrote its before/after PNGs to a hardcoded /home/scott/npu-linux-kit/camera/... path, which only works on the original machine. Changed it to write next to the script using the os.path.dirname(__file__) pattern the file already uses for sys.path. Still needs the real NPU + IRON toolchain to run end to end (import aie.iron), so I couldn't execute it, but the path fix is a one-line, low-risk portability correction.

CI

Every module in this kit sits on top of the open-xdna NPU stack (IRON/mlir-aie + Peano + a real XDNA1 chip), none of which exists on a GitHub-hosted runner. This CI covers what's actually checkable:

• Byte-compiles all of camera/*.py (syntax only)
• Installs requirements.txt (opencv-python-headless, onnxruntime, numpy, ml_dtypes, pyvirtualcam) in a clean venv - confirms the host-side deps resolve on Linux/x86_64
• Runs each camera/*.py module and checks it gets through all of its own host-side imports and fails only at import aie.iron (the NPU-toolchain boundary). Any other failure mode is a real bug and fails CI.

I ran this exact sequence locally first: requirements.txt installs clean, and all six camera/*.py files (including test_blur.py after the path fix) fail only at the aie import, nothing earlier.

What this does NOT verify (said explicitly in the workflow comments)

• Any effect actually running on the NPU
• camera/kernels/blur3x3.cc compiling - needs the Peano AIE2 cross-compiler and aie_api headers
• Any of the measured FPS numbers in camera/README.md

Test plan

• python -m compileall -q camera clean
• pip install -r requirements.txt clean in a fresh venv
• All 6 camera/*.py files fail only at ModuleNotFoundError: No module named 'aie', verified locally