feat: initial CamWatch service

Polls Frigate events API, extracts dominant vehicle color (KMeans),
reads LPR plate from Frigate sub_label. Responsive dark UI with
filter by plate/camera/date and auto-refresh. FastAPI + SQLite.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,13 @@
+FROM python:3.11-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libgl1 libglib2.0-0 \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+COPY app/requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY app/ .
+
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]