feat(api): 统一公开接口为 /api/v1 前缀

将通用生成、Gemini、可灵、火山、健康检查与 OpenAPI 的推荐入口统一到 /api/v1，并保留历史路径作为兼容别名。同步更新代理配置、接入文档、接口清单和前缀回归测试。\n\n验证：go vet ./...；go test ./...；pnpm openapi；pnpm lint；pnpm test；pnpm build；公开 OpenAPI 71 个方法与接口清单机器比对一致。

deploy/nginx/ai.51easyai.com-api-v1.inc

@@ -0,0 +1,19 @@
+# Include inside the TLS server block for ai.51easyai.com.
+# The application owns routing below /api/v1; the edge proxy preserves the URI.
+
+location = /api/v1/metrics {
+  return 404;
+}
+
+location ^~ /api/v1/ {
+  proxy_http_version 1.1;
+  proxy_set_header Host $host;
+  proxy_set_header X-Real-IP $remote_addr;
+  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+  proxy_set_header X-Forwarded-Proto $scheme;
+  proxy_set_header Connection "";
+  proxy_buffering off;
+  proxy_read_timeout 3600s;
+  proxy_send_timeout 3600s;
+  proxy_pass http://127.0.0.1:8088;
+}