feat: add role management and usage tracking for AI code review

- Implemented role parsing and loading from markdown files, including attributes like name, side, focus, badge, color, and personality.
- Created functions to build prompts for analysis, line location, and verdicts based on roles.
- Added tests for role management functionalities to ensure correct parsing and loading of roles.
- Developed usage tracking for AI assistant interactions, including token usage and rate limits.
- Implemented functions to extract and record usage data from various LLM providers.
- Added tests for usage tracking functionalities to validate correct accumulation and reporting of usage statistics.

app/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "ai-code-review",
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "test": "node --test *.test.js"
+  },
+  "dependencies": {
+    "axios": "^1.6.7",
+    "js-yaml": "^4.1.0",
+    "openai": "^4.28.0"
+  }
+}