feat(ai): Migrate tests to Vitest and add provider test coverage

- Switch from Node.js test runner to Vitest for better DX
- Add test suites for Grok, Groq, Cerebras, and OpenRouter providers
- Add Ollama test suite with automatic server lifecycle management
- Include thinking mode and multi-turn tests for all providers
- Remove example files (consolidated into test suite)
- Add VS Code test configuration

packages/ai/package.json

@@ -15,7 +15,9 @@
 		"generate-models": "npx tsx scripts/generate-models.ts",
 		"build": "npm run generate-models && tsc -p tsconfig.build.json && cp src/models.json dist/models.json",
 		"check": "biome check --write .",
-		"test": "npx tsx --test test/providers.test.ts",
+		"test": "vitest",
+		"test:ui": "vitest --ui",
+		"test:old": "npx tsx --test test/providers.test.ts",
 		"extract-models": "npx tsx scripts/extract-openai-models.ts",
 		"prepublishOnly": "npm run clean && npm run models && npm run build"
 	},
@@ -45,6 +47,8 @@
 		"node": ">=20.0.0"
 	},
 	"devDependencies": {
-		"@types/node": "^24.3.0"
+		"@types/node": "^24.3.0",
+		"@vitest/ui": "^3.2.4",
+		"vitest": "^3.2.4"
 	}
 }