fix(dashboard): agent bridge dns toggle uses POST, not PUT (#7157) (#7197)

The dns toggle button called fetch(..., { method: "PUT" }) but
src/app/api/tools/agent-bridge/agents/[id]/dns/route.ts only exports
POST, so Next.js auto-returned 405 on every Start/Stop DNS click.
Fixes the frontend caller to match the documented POST contract
(docs/frameworks/AGENTBRIDGE.md:490) already covered by
tests/unit/agent-bridge-dns-route-validation.test.ts.

Adds a regression test asserting the fetch call uses method: POST.

changelog.d/fixes/7157-agent-bridge-dns-405.md

@@ -0,0 +1 @@
+- fix(dashboard): Agent Bridge DNS toggle now sends POST (was PUT), fixing HTTP 405 on Start/Stop DNS (#7157)

src/app/(dashboard)/dashboard/tools/agent-bridge/AgentBridgePageClient.tsx

@@ -147,7 +147,7 @@ export default function AgentBridgePageClient({
       setActionError(null);
       try {
         const res = await fetch(`/api/tools/agent-bridge/agents/${agentId}/dns`, {
-          method: "PUT",
+          method: "POST",
           headers: { "Content-Type": "application/json" },
           body: JSON.stringify({ enabled }),
         });

tests/unit/agent-bridge-dns-toggle-method-7157.test.ts

@@ -0,0 +1,24 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import path from "node:path";
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const clientPath = path.resolve(
+  __dirname,
+  "../../src/app/(dashboard)/dashboard/tools/agent-bridge/AgentBridgePageClient.tsx"
+);
+const source = readFileSync(clientPath, "utf8");
+
+test("#7157: dns toggle fetch call uses method POST (route.ts only exports POST)", () => {
+  const dnsCallMatch = source.match(
+    /\/api\/tools\/agent-bridge\/agents\/\$\{agentId\}\/dns`,\s*\{\s*method:\s*"([A-Z]+)"/
+  );
+  assert.ok(dnsCallMatch, "expected to find the dns fetch call in AgentBridgePageClient.tsx");
+  assert.equal(
+    dnsCallMatch?.[1],
+    "POST",
+    "dns fetch call must use method: 'POST' to match the route.ts export (issue #7157)"
+  );
+});