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

package.json

@@ -7,7 +7,8 @@
   ],
   "scripts": {
     "build": "bun run --filter '*' build",
-    "check": "biome check .",
+    "check": "bunx tsc --build && biome check .",
+    "typecheck": "bunx tsc --build",
     "format": "biome format --write .",
     "test": "bun run --filter '*' test"
   },