feat: add available_regions to recommendations

- Add AvailableRegion interface in types.ts
- Show all regions where the same server spec is available
- Helps users see regional options (e.g., Tokyo and Osaka for japan)
- Sorted by price, excludes current region

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

src/handlers/recommend.ts

@@ -12,7 +12,8 @@ import type {
   BandwidthEstimate,
   RecommendationResult,
   BenchmarkReference,
-  AIRecommendationResponse
+  AIRecommendationResponse,
+  AvailableRegion
 } from '../types';
 import { i18n, LIMITS } from '../config';
 import {
@@ -1054,6 +1055,20 @@ The option with the LOWEST TOTAL MONTHLY COST (including bandwidth) should have
       // Calculate bandwidth info for this server
       const bandwidthInfo = calculateBandwidthInfo(server, bandwidthEstimate);
 
+      // Find all available regions for the same server spec
+      const availableRegions: AvailableRegion[] = candidates
+        .filter(c =>
+          c.provider_name === server.provider_name &&
+          c.instance_id === server.instance_id &&
+          c.region_code !== server.region_code  // Exclude current region
+        )
+        .map(c => ({
+          region_name: c.region_name,
+          region_code: c.region_code,
+          monthly_price: c.monthly_price
+        }))
+        .sort((a, b) => a.monthly_price - b.monthly_price);
+
       results.push({
         server: server,
         score: aiRec.score,
@@ -1070,6 +1085,7 @@ The option with the LOWEST TOTAL MONTHLY COST (including bandwidth) should have
               performance_per_dollar: matchingVPS.performance_per_dollar,
             }
           : undefined,
+        available_regions: availableRegions.length > 0 ? availableRegions : undefined,
       });
 
       if (results.length >= 3) break;