feat: proxy provider UI, webhook URL fix, and dev-server key persistence

- Add proxy provider selector (None/NPM) to settings page with radio cards
- Show warning when switching to None about existing NPM routes
- Conditionally hide SSL certificate picker and NPM credentials when provider is None
- Fix webhook URL regenerate not updating UI (field name mismatch: url vs webhook_url)
- Fix dev-server.sh to persist ENCRYPTION_KEY across restarts via data/.dev-key
- Fix selected radio card background visibility in dark mode

web/src/lib/api.ts

@@ -260,12 +260,12 @@ export function updateSettings(data: Partial<Settings>): Promise<Settings> {
 	return put<Settings>('/api/settings', data);
 }
 
-export function getWebhookUrl(): Promise<{ url: string }> {
-	return get<{ url: string }>('/api/settings/webhook-url');
+export function getWebhookUrl(): Promise<{ webhook_url: string }> {
+	return get<{ webhook_url: string }>('/api/settings/webhook-url');
 }
 
-export function regenerateWebhookUrl(): Promise<{ url: string }> {
-	return post<{ url: string }>('/api/settings/webhook-url/regenerate');
+export function regenerateWebhookUrl(): Promise<{ webhook_url: string }> {
+	return post<{ webhook_url: string }>('/api/settings/webhook-url/regenerate');
 }
 
 export function listNpmCertificates(): Promise<NpmCertificate[]> {