chore(ci): optimize Dockerfile layer order to cache Python dependency installation

Reorder COPY and RUN instructions in both Dockerfile and Dockerfile.server
to leverage Docker's layer caching for the dependency installation step.

Previously, pyproject.toml, README.md, and src/ were all copied together
before running uv pip install, meaning any source code change would
invalidate the dependency layer cache and force a full reinstall.

The new pattern copies only the dependency manifests (pyproject.toml and
uv.lock) first, installs the build tool in a cached layer, then copies
README.md and src/ for the actual wheel build. This ensures the
uv pip install step is only re-executed when pyproject.toml or uv.lock
change, not on every source code change.

ISSUES CLOSED: #1667

Dockerfile

@@ -12,13 +12,21 @@ COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
 # Set up working directory
 WORKDIR /app
 
-# Copy project metadata and source code
-COPY pyproject.toml README.md ./
+# Copy dependency manifests first to leverage Docker layer caching.
+# The expensive dependency installation step is only re-executed when
+# pyproject.toml or uv.lock change, not on every source code change.
+COPY pyproject.toml uv.lock ./
+
+# Install build tool — this layer is cached as long as pyproject.toml
+# and uv.lock remain unchanged.
+RUN uv pip install --system build
+
+# Copy remaining source files needed for the wheel build.
+COPY README.md ./
 COPY src/ ./src/
 
 # Build wheel
-RUN uv pip install --system build && \
-    python -m build --wheel --outdir /dist
+RUN python -m build --wheel --outdir /dist
 
 # Runtime stage
 FROM python:3.13-slim

Dockerfile.server

@@ -22,13 +22,19 @@ COPY --from=ghcr.io/astral-sh/uv:0.8.0 /uv /usr/local/bin/uv
 
 WORKDIR /app
 
-# Copy project metadata and source code
-COPY pyproject.toml README.md ./
-COPY src/ ./src/
+# Copy dependency manifests first to leverage Docker layer caching.
+# The expensive dependency installation step is only re-executed when
+# pyproject.toml or uv.lock change, not on every source code change.
+COPY pyproject.toml uv.lock ./
 
-# Install build tool (separate layer for better caching)
+# Install build tool (separate layer for better caching) — this layer is
+# cached as long as pyproject.toml and uv.lock remain unchanged.
 RUN uv pip install --system build
 
+# Copy remaining source files needed for the wheel build.
+COPY README.md ./
+COPY src/ ./src/
+
 # Build wheel
 RUN python -m build --wheel --outdir /dist