feat(tenant-api): expose Swagger UI in non-release mode

Adds an in-process Swagger UI and OpenAPI JSON under /swagger,
registered automatically when the Gin mode is not release. The
admin-web Vite dev server and production nginx config now proxy
/swagger to the tenant API so the docs are reachable from the
existing admin host.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/admin-web/vite.config.ts

@@ -58,6 +58,10 @@ export default defineConfig(({ mode }) => {
           target: env.VITE_API_PROXY_TARGET || "http://localhost:8080",
           changeOrigin: true,
         },
+        "/swagger": {
+          target: env.VITE_API_PROXY_TARGET || "http://localhost:8080",
+          changeOrigin: true,
+        },
       },
     },
     esbuild: isProd ? { drop: ["console", "debugger"] } : undefined,