fix(proxy): test endpoint resolves real credentials from DB via proxyId

The proxy test button in Settings was always failing with 'Socks5 Authentication
failed' because the frontend sent redacted credentials (***) from listProxies().
The backend received '***' as the password and tried to authenticate with it.

Fix: Frontend now sends proxyId in the test request body. The test endpoint
looks up the proxy from the DB with includeSecrets: true and uses the real
stored credentials for the SOCKS5 handshake.

Also: removed username/password from the frontend test payload since they
are always redacted and useless for testing.

src/app/(dashboard)/dashboard/settings/components/ProxyRegistryManager.tsx

@@ -209,12 +209,11 @@ export default function ProxyRegistryManager() {
         method: "POST",
         headers: { "Content-Type": "application/json" },
         body: JSON.stringify({
+          proxyId: item.id,
           proxy: {
             type: item.type || "http",
             host: item.host,
             port: String(item.port || 8080),
-            username: item.username,
-            password: item.password,
           },
         }),
       });

src/app/api/settings/proxy/test/route.ts

@@ -8,6 +8,7 @@ import {
 import { testProxySchema } from "@/shared/validation/schemas";
 import { isValidationFailure, validateBody } from "@/shared/validation/helpers";
 import { createErrorResponse, createErrorResponseFromUnknown } from "@/lib/api/errorResponse";
+import { getProxyById } from "@/lib/localDb";
 
 const BASE_SUPPORTED_PROXY_TYPES = new Set(["http", "https"]);
 
@@ -56,7 +57,26 @@ export async function POST(request: Request) {
         type: "invalid_request",
       });
     }
-    const { proxy } = validation.data;
+    let { proxy } = validation.data;
+
+    // If a proxyId is provided, look up the real (non-redacted) credentials from DB.
+    // The frontend sends redacted credentials (***) from listProxies(), so we need
+    // the actual secrets for testing.
+    const body = rawBody as Record<string, unknown>;
+    const proxyId = typeof body.proxyId === "string" ? body.proxyId.trim() : null;
+    if (proxyId) {
+      const dbProxy = await getProxyById(proxyId, { includeSecrets: true });
+      if (dbProxy) {
+        proxy = {
+          ...proxy,
+          host: proxy.host || dbProxy.host,
+          port: proxy.port || String(dbProxy.port),
+          type: proxy.type || dbProxy.type,
+          username: dbProxy.username,
+          password: dbProxy.password,
+        };
+      }
+    }
 
     const proxyType = String(proxy.type || "http").toLowerCase();
     if (proxyType === "socks5" && !isSocks5ProxyEnabled()) {