fix: add corepack cache dir to Dockerfile (GRO-655)

Adds mkdir -p /home/node/.cache/node/corepack in builder stage to fix ENOENT crash in migration/seed jobs.

Root cause: c438f57 image regression — container user's home cache directory not pre-created for corepack.

Blocking: GRO-618 (UAT promotion), GRO-607 (payment UI), GRO-609

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/Dockerfile

@@ -12,6 +12,7 @@ RUN pnpm install --frozen-lockfile
 
 # Build
 FROM deps AS builder
+RUN mkdir -p /home/node/.cache/node/corepack
 COPY packages/ packages/
 COPY apps/api/ apps/api/
 RUN pnpm --filter @groombook/types build && \
@@ -49,4 +50,4 @@ CMD ["pnpm", "db:seed"]
 
 # Reset stage — drops all tables, re-runs migrations, and re-seeds
 FROM builder AS reset
-CMD ["pnpm", "db:reset"]
+CMD ["pnpm", "db:reset"]