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/generated/client-optimized/app.js

@@ -0,0 +1,62 @@
+export { matchers } from './matchers.js';
+
+export const nodes = [
+	() => import('./nodes/0'),
+	() => import('./nodes/1'),
+	() => import('./nodes/2'),
+	() => import('./nodes/3'),
+	() => import('./nodes/4'),
+	() => import('./nodes/5'),
+	() => import('./nodes/6'),
+	() => import('./nodes/7'),
+	() => import('./nodes/8'),
+	() => import('./nodes/9'),
+	() => import('./nodes/10'),
+	() => import('./nodes/11'),
+	() => import('./nodes/12'),
+	() => import('./nodes/13'),
+	() => import('./nodes/14'),
+	() => import('./nodes/15'),
+	() => import('./nodes/16'),
+	() => import('./nodes/17'),
+	() => import('./nodes/18'),
+	() => import('./nodes/19')
+];
+
+export const server_loads = [];
+
+export const dictionary = {
+		"/": [3],
+		"/containers/stale": [4],
+		"/deploy": [5],
+		"/events": [6],
+		"/login": [7],
+		"/projects": [8],
+		"/projects/[id]": [9],
+		"/projects/[id]/env": [10],
+		"/projects/[id]/volumes": [11],
+		"/projects/[id]/volumes/[volId]/browse": [12],
+		"/proxies": [13],
+		"/proxies/create": [14],
+		"/proxies/[id]/edit": [15],
+		"/settings": [16,[2]],
+		"/settings/auth": [17,[2]],
+		"/settings/credentials": [18,[2]],
+		"/settings/registries": [19,[2]]
+	};
+
+export const hooks = {
+	handleError: (({ error }) => { console.error(error) }),
+	
+	reroute: (() => {}),
+	transport: {}
+};
+
+export const decoders = Object.fromEntries(Object.entries(hooks.transport).map(([k, v]) => [k, v.decode]));
+export const encoders = Object.fromEntries(Object.entries(hooks.transport).map(([k, v]) => [k, v.encode]));
+
+export const hash = false;
+
+export const decode = (type, value) => decoders[type](value);
+
+export { default as root } from '../root.js';