fix: resolve TypeScript and linting errors in test infrastructure

- Add @types/better-sqlite3 dependency
- Remove duplicate database mock file
- Fix property spread order in workflow builder to prevent overwrites
- All 75 tests now pass with no linting errors

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

package-lock.json

@@ -26,6 +26,7 @@
       "devDependencies": {
         "@faker-js/faker": "^9.9.0",
         "@testing-library/jest-dom": "^6.6.4",
+        "@types/better-sqlite3": "^7.6.13",
         "@types/express": "^5.0.3",
         "@types/node": "^22.15.30",
         "@types/ws": "^8.18.1",
@@ -13679,6 +13680,16 @@
         "@babel/types": "^7.20.7"
       }
     },
+    "node_modules/@types/better-sqlite3": {
+      "version": "7.6.13",
+      "resolved": "https://registry.npmjs.org/@types/better-sqlite3/-/better-sqlite3-7.6.13.tgz",
+      "integrity": "sha512-NMv9ASNARoKksWtsq/SHakpYAYnhBrQgGD8zkLYk/jaK8jUGn08CfEdTRgYhMypUQAfzSP8W6gNLe0q19/t4VA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/node": "*"
+      }
+    },
     "node_modules/@types/body-parser": {
       "version": "1.19.6",
       "resolved": "https://registry.npmjs.org/@types/body-parser/-/body-parser-1.19.6.tgz",