fix(docker): README.md for hatchling (#32)

pyproject.toml names README.md as the readme; hatchling validates that
file exists when uv sync resolves the editable install of the project
itself. Caught on second deploy build.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -46,9 +46,11 @@ RUN curl -LsSf https://astral.sh/uv/install.sh | sh \
 
 WORKDIR /app
 
-# Copy just the dependency manifests first so the heavy `uv sync` layer
+# Copy dependency manifests + README early so the heavy `uv sync` layer
-# caches whenever only application code changes.
+# caches whenever only application code changes. README.md is required
-COPY pyproject.toml uv.lock .python-version ./
+# because pyproject.toml names it as the package's readme — hatchling
+# validates it exists when resolving the editable install.
+COPY pyproject.toml uv.lock .python-version README.md ./
 
 # Prod + OCR extras, no dev tooling. --frozen means "must match uv.lock";
 # CI catches drift before it reaches the image.