refactor: extract common bandwidth formatting utilities

- Add BandwidthInfo interface to types.ts (single source of truth)
- Create formatters.ts with formatTB() and formatTrafficInfo()
- Display CDN hit rate and gross/origin traffic in recommendations
- Fix floating point formatting (consistent decimal places)
- Fix undefined handling in toLocaleString() calls
- Unify overage detection logic (overage_tb > 0 && cost > 0)
- Add CDN hit rate range validation (0-100%)
- Extract CDN_CACHE_HIT_RATES constants

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/server-agent.ts

@@ -9,9 +9,10 @@
  * - Brave Search / Context7 도구로 최신 트렌드 반영
  */
 
-import type { Env, ServerSession } from './types';
+import type { Env, ServerSession, BandwidthInfo } from './types';
 import { createLogger } from './utils/logger';
 import { executeSearchWeb, executeLookupDocs } from './tools/search-tool';
+import { formatTrafficInfo } from './utils/formatters';
 
 const logger = createLogger('server-agent');
 
@@ -215,11 +216,7 @@ interface RecommendResponse {
     estimated_capacity?: {
       max_concurrent_users?: number;
     };
-    bandwidth_analysis?: {
-      estimated_monthly_tb?: number;
-      overage_tb?: number;
-      overage_cost_krw?: number;
-    };
+    bandwidth_info?: BandwidthInfo;
   }>;
 }
 
@@ -561,12 +558,32 @@ export async function processServerConsultation(
             plan: selected.plan_name
           });
 
+          // 트래픽 정보 포맷팅
+          let trafficInfo = '';
+          if (selected.price.estimated_monthly_tb !== undefined) {
+            const bandwidthInfo: BandwidthInfo = {
+              included_transfer_tb: selected.price.bandwidth_tb,
+              overage_cost_per_gb: 0,
+              overage_cost_per_tb: 0,
+              estimated_monthly_tb: selected.price.estimated_monthly_tb,
+              estimated_overage_tb: selected.price.overage_tb || 0,
+              estimated_overage_cost: selected.price.overage_cost_krw || 0,
+              total_estimated_cost: selected.price.monthly_krw + (selected.price.overage_cost_krw || 0),
+              currency: 'KRW',
+              gross_monthly_tb: selected.price.gross_monthly_tb,
+              cdn_cache_hit_rate: selected.price.cdn_cache_hit_rate,
+            };
+            trafficInfo = `• ${formatTrafficInfo(bandwidthInfo, 'KRW')}\n`;
+          }
+
           return `🖥️ ${selected.plan_name} 신청 확인\n\n` +
             `• 제공사: ${selected.provider}\n` +
-            `• 스펙: ${selected.specs.vcpu}vCPU / ${selected.specs.ram_gb}GB / ${selected.specs.storage_gb}GB\n` +
+            `• 스펙: ${selected.specs.vcpu}vCPU / ${selected.specs.ram_gb}GB RAM / ${selected.specs.storage_gb}GB SSD\n` +
             `• 리전: ${selected.region.name} (${selected.region.code})\n` +
-            `• 가격: ₩${selected.price.monthly_krw.toLocaleString()}/월\n\n` +
-            `신청하시겠습니까?\n\n` +
+            `• 가격: ₩${selected.price.monthly_krw.toLocaleString()}/월\n` +
+            `• 대역폭: ${selected.price.bandwidth_tb}TB 포함\n` +
+            trafficInfo +
+            `\n신청하시겠습니까?\n\n` +
             `__KEYBOARD__${keyboardData}__END__`;
         } else {
           return `번호를 다시 확인해주세요. 1번부터 ${session.lastRecommendation.recommendations.length}번 중에서 선택해주세요.`;
@@ -646,7 +663,12 @@ export async function processServerConsultation(
             },
             price: {
               monthly_krw: Math.round(rec.server.monthly_price),
-              bandwidth_tb: rec.server.transfer_tb
+              bandwidth_tb: rec.server.transfer_tb,
+              estimated_monthly_tb: rec.bandwidth_info?.estimated_monthly_tb,
+              gross_monthly_tb: rec.bandwidth_info?.gross_monthly_tb,
+              cdn_cache_hit_rate: rec.bandwidth_info?.cdn_cache_hit_rate,
+              overage_tb: rec.bandwidth_info?.estimated_overage_tb,
+              overage_cost_krw: rec.bandwidth_info?.estimated_overage_cost
             },
             score: rec.score,
             max_users: rec.estimated_capacity?.max_concurrent_users || 0