fix: add pregenerate cleanup to SDK packages to remove stale files

Each generate script now cleans its output directory via rimraf before
running codegen. This prevents stale files from deleted database
entities from persisting and causing build failures.

Affected packages:
- constructive-sdk: cleans src/{admin,auth,objects,public}
- constructive-cli: cleans src/{admin,auth,objects,public}
- constructive-react: cleans src/{admin,auth,objects,public}
- migrate-client (via constructive-sdk): cleans src/migrate

Author: pyramation

package.json

@@ -39,6 +39,7 @@
     "lerna": "^8.2.3",
     "makage": "^0.1.12",
     "prettier": "^3.8.1",
+    "rimraf": "^6.1.3",
     "ts-jest": "^29.4.6",
     "ts-node": "^10.9.2",
     "typescript": "^5.1.6"