fix(workflow): add typecheck script and fix remaining type errors

- Add typecheck script (bunx tsc --build) to package.json
- Update check script to run typecheck before biome
- Fix mock fetch casts in test files (bun-types preconnect)
- Fix RequestInfo → Request | string | URL in llm-extract test
- Fix ThreadContext generic cast in solve-issue-template test
- Fix git-exec.ts missing return and module resolution
- Remove @types/node from workflow-role-committer
- Add exports field to workflow-util-agent/package.json

packages/workflow-util-agent/package.json

@@ -4,6 +4,12 @@
   "type": "module",
   "main": "src/index.ts",
   "types": "src/index.ts",
+  "exports": {
+    ".": {
+      "types": "./src/index.ts",
+      "default": "./src/index.ts"
+    }
+  },
   "scripts": {
     "build": "echo 'TODO'",
     "test": "bun test"