build(docker): GPU-ready test image for .9 (CUDA 12.4 + py3.11 + node22/ffmpeg)

Bundles the M1 milestone: mock voice pipeline (wsai) + dave/ selfbot voice
joiner. Entrypoint dispatches smoke/voice/mock/gpu/join/shell. .env mounted at
runtime (not baked). Built GPU-capable via NVIDIA CDI so later STT/TTS drop in.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,8 @@
+.venv/
+**/__pycache__/
+*.pyc
+.pytest_cache/
+dave/node_modules/
+poc/frames/
+.git
+.env