fix(deploy): drop COPY data/ from Dockerfile so worktree-context staging build succeeds

The ORCH-058 staging rebuild (check_staging_image_fresh) builds the image with
the task git-worktree as the docker build context. A fresh worktree holds only
tracked files, but the Dockerfile did `COPY data/ ./data/` — and `data/` (the
SQLite dir) is gitignored, so it is absent from that context: `docker build`
failed with exit 1 ("BUILD-STAGING: docker build failed - aborting"), bouncing
the task off deploy-staging back to development in a loop.

The COPY was dead weight regardless: `data/` is always supplied at runtime as a
bind-mount volume (./data:/app/data, see docker-compose.yml) which shadows
anything baked into the image. Replace it with `RUN mkdir -p /app/data` so the
mountpoint exists without depending on the build context.

Regression guard: test_tc08b_dockerfile_does_not_copy_gitignored_data_dir
forbids COPY of any gitignored path (the worktree-context invariant).

Refs: ORCH-021

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

Dockerfile

@@ -20,6 +20,13 @@ RUN groupadd -g 1000 app && useradd -u 1000 -g 1000 -m -d /home/slin -s /bin/bas
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 COPY src/ ./src/
-COPY data/ ./data/
+# ORCH-021: do NOT `COPY data/ ./data/`. `data/` is gitignored (SQLite DB dir) and
+# is provided at runtime as a bind-mount volume (`./data:/app/data`, see
+# docker-compose.yml) which shadows anything baked into the image — so the COPY was
+# dead weight. Worse, the ORCH-058 staging rebuild (`check_staging_image_fresh`)
+# builds with the task *worktree* as the docker build context; a fresh worktree never
+# contains the untracked `data/`, so `COPY data/` failed `docker build` with exit 1
+# and bounced the task off `deploy-staging`. We just ensure the mountpoint exists.
+RUN mkdir -p /app/data
 ENV PYTHONPATH=/app
 CMD ["uvicorn", "src.main:app", "--host", "0.0.0.0", "--port", "8500"]