fix KV API to unified format, and test

package.json

@@ -7,7 +7,10 @@
   "scripts": {
     "build": "tsc",
     "start": "node dist/index.js",
-    "dev": "tsx watch src/index.ts"
+    "dev": "tsx watch src/index.ts",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:coverage": "vitest run --coverage"
   },
   "dependencies": {
     "fastify": "^5.0.0",
@@ -16,8 +19,10 @@
   "devDependencies": {
     "@types/fluent-ffmpeg": "^2.1.24",
     "@types/node": "^20.0.0",
+    "@vitest/coverage-v8": "^1.0.0",
     "tsx": "^4.0.0",
-    "typescript": "^5.3.0"
+    "typescript": "^5.3.0",
+    "vitest": "^1.0.0"
   },
   "engines": {
     "node": ">=20.0.0"