fix: use root pnpm build instead of --filter for api in Dockerfile

pnpm --filter @groombook/api doesn't match the workspace root package
because pnpm-workspace.yaml only includes packages/*. The root
package.json already has a build script that compiles src/ → dist/,
which is what the Dockerfile copies.

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

Dockerfile

@@ -17,7 +17,7 @@ COPY src/ src/
 COPY tsconfig.json ./
 RUN pnpm --filter @groombook/types build && \
     pnpm --filter @groombook/db build && \
-    pnpm --filter @groombook/api build
+    pnpm build
 
 # Runtime
 FROM node:22-alpine AS runner