feat: add Vitest test infrastructure for agent and script validation (#337)

Adds Vitest + TypeScript test infrastructure for agent validation. Validates 642 agent files across 14 categories for YAML frontmatter, kebab-case naming, and directory population.

tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "outDir": "dist",
+    "rootDir": "."
+  },
+  "include": ["tests/**/*.ts", "vitest.config.ts"]
+}