fix: address code review findings for DNS management

- CRITICAL: Change DNS zones endpoint from GET to POST to avoid
  leaking API token in URL query parameters
- HIGH: Add sync.RWMutex to protect dnsProvider field in Server,
  Deployer, and proxy Manager against concurrent read/write races
- HIGH: Capture old DNS provider reference synchronously before
  launching background cleanup goroutine
- HIGH: Use getDNS()/getDNSProviderLocked() accessors instead of
  direct field reads in all DNS operations

web/.svelte-kit/output/server/chunks/stores.js

@@ -0,0 +1,32 @@
+import { j as getContext } from "./index.js";
+import "clsx";
+import "@sveltejs/kit/internal";
+import "./exports.js";
+import "./utils.js";
+import "@sveltejs/kit/internal/server";
+import "./root.js";
+import "./state.svelte.js";
+const getStores = () => {
+  const stores$1 = getContext("__svelte__");
+  return {
+    /** @type {typeof page} */
+    page: {
+      subscribe: stores$1.page.subscribe
+    },
+    /** @type {typeof navigating} */
+    navigating: {
+      subscribe: stores$1.navigating.subscribe
+    },
+    /** @type {typeof updated} */
+    updated: stores$1.updated
+  };
+};
+const page = {
+  subscribe(fn) {
+    const store = getStores().page;
+    return store.subscribe(fn);
+  }
+};
+export {
+  page as p
+};