chore(build): remove redundant build:types step (#1636)

## Summary

`rollup-plugin-typescript2` already emits all `.d.ts` files into
`dist/typings/` as part of the standard Rollup build. The separate
`build:types` step added in #1574 produces identical output, making it
redundant.

Also improves the `verify-types` CI job to use `npm pack --dry-run`
which directly catches the failure mode from #1573 (typings missing from
published package) rather than just checking local file existence.

## Changes

- Remove `build:types` script from `package.json`
- Simplify `prepack` to `npm run build` only
- Delete `tsconfig.types.json` (no longer referenced)
- Update `verify-types` CI job to verify typings are included in the
published package via `npm pack --dry-run`

## Test plan

- [x] `npm run build` generates 44 `.d.ts` files in `dist/typings/`
- [x] `npm pack --dry-run` shows 44 typings files included in package
- [x] All 998 unit tests pass

Author: yogeshchoudhary147

.github/workflows/test.yml

@@ -99,8 +99,11 @@ jobs:
           path: .
           key: ${{ env.CACHE_KEY }}
 
-      - name: Generate type declarations
-        run: npm run build:types
+      - name: Verify type declarations
+        run: |
+          count=$(npm pack --dry-run 2>&1 | grep -c "dist/typings/" || true)
+          echo "Found $count typings files in package"
+          test "$count" -gt 0 || { echo "typings not included in package!"; exit 1; }
 
   gatsby:
     needs: test

package.json

@@ -33,7 +33,6 @@
     "start": "npm run dev",
     "docs": "typedoc --options ./typedoc.js src",
     "build": "rimraf dist && rollup -m -c --environment NODE_ENV:production && npm run test:es-check",
-    "build:types": "tsc --project tsconfig.types.json",
     "build:stats": "rimraf dist && rollup -m -c --environment NODE_ENV:production --environment WITH_STATS:true && npm run test:es-check && open bundle-stats/index.html",
     "lint": "eslint --ext .jsx,.js src/",
     "lint:security": "eslint ./src --ext ts --no-eslintrc --config ./.eslintrc.security",
@@ -51,7 +50,7 @@
     "serve:coverage": "serve coverage/lcov-report -n",
     "serve:stats": "serve bundle-stats -n",
     "print-bundle-size": "node ./scripts/print-bundle-size.mjs",
-    "prepack": "npm run build && npm run build:types",
+    "prepack": "npm run build",
     "publish:cdn": "ccu --trace"
   },
   "devDependencies": {