fix(docker): declare esbuild as direct dev dependency

The Dockerfile uses `pnpm exec esbuild` to bundle the migrator into a
single ESM file before copying it into the runtime image. pnpm exec only
resolves binaries from declared dependencies, so the transitive esbuild
that tsx pulls in wasn't visible to the build stage.

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

apps/web/package.json

@@ -30,6 +30,7 @@
     "@types/react": "^19.0.2",
     "@types/react-dom": "^19.0.2",
     "drizzle-kit": "^0.30.1",
+    "esbuild": "^0.24.2",
     "eslint": "^9.17.0",
     "eslint-config-next": "^15.1.0",
     "tsx": "^4.19.2",