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/log.js

@@ -0,0 +1,38 @@
+export function section(title) {
+  console.log(`\n=== ${title} ===`);
+}
+
+export function step(stepName, title) {
+  console.log(`\n[${stepName}] ${title}`);
+}
+
+export function line(message) {
+  console.log(`  - ${message}`);
+}
+
+/** 階段輸入：這個階段吃進什麼。 */
+export function input(message) {
+  console.log(`  ← 輸入：${message}`);
+}
+
+/** 階段輸出：這個階段產出什麼。 */
+export function output(message) {
+  console.log(`  → 輸出：${message}`);
+}
+
+/** 檢查／把關結果：明確標示成功或失敗。 */
+export function result(passed, message) {
+  console.log(`  ${passed ? '✅ 成功' : '❌ 失敗'}：${message}`);
+}
+
+export function ok(message) {
+  console.log(`  ✓ ${message}`);
+}
+
+export function warn(message) {
+  console.warn(`  ! ${message}`);
+}
+
+export function error(message) {
+  console.error(`  x ${message}`);
+}