fix: prediction proxy rewrite 경로 수정

/api/prediction → rewrite: '' → '/api'
기존: /api/prediction/v1/... → /v1/... (404 - FastAPI 라우트 불일치)
수정: /api/prediction/v1/... → /api/v1/... (정상 매칭)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/vite.config.ts

@@ -118,7 +118,7 @@ export default defineConfig(({ mode }): UserConfig => ({
       '/api/prediction': {
         target: 'http://localhost:8001',
         changeOrigin: true,
-        rewrite: (path) => path.replace(/^\/api\/prediction/, ''),
+        rewrite: (path) => path.replace(/^\/api\/prediction/, '/api'),
       },
       '/ollama': {
         target: 'http://localhost:11434',