Configure monorepo build: unified CI, local deps, .dockerignore

- Dockerfiles use monorepo root as build context
- common/ and core/ installed as local packages (no git+https)
- Client tarball built from local client/ dir
- Unified CI with change detection: common/core -> rebuild both
- Per-repo CI workflows removed

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

l1/Dockerfile.gpu

@@ -60,7 +60,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 RUN python3 -m pip install --upgrade pip
 
 # Install CPU dependencies first
-COPY requirements.txt .
+COPY l1/requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
 # Install GPU-specific dependencies (CuPy for CUDA 12.x)
@@ -74,11 +74,16 @@ COPY --from=builder /decord-install /usr/local/lib/python3.11/dist-packages/
 COPY --from=builder /tmp/decord/build/libdecord.so /usr/local/lib/
 RUN ldconfig
 
+# Install monorepo shared packages
+COPY common/ /tmp/common/
+COPY core/ /tmp/core/
+RUN pip install --no-cache-dir /tmp/common/ /tmp/core/ && rm -rf /tmp/common /tmp/core
+
 # Clone effects repo (before COPY so it gets cached)
 RUN git clone https://git.rose-ash.com/art-dag/effects.git /app/artdag-effects
 
 # Copy application (this invalidates cache for any code change)
-COPY . .
+COPY l1/ .
 
 # Create cache directory
 RUN mkdir -p /data/cache