feat: add per-API connection proxy URL settings

src/services/providerProxy.ts

@@ -0,0 +1,21 @@
+export function normalizeProviderProxyUrl(value: string): string {
+  const proxyUrl = value.trim();
+  if (!proxyUrl) return '';
+  if (/^(direct|none)$/i.test(proxyUrl)) return proxyUrl.toLowerCase();
+
+  try {
+    if (/\s/.test(proxyUrl)) throw new Error('invalid');
+    const url = new URL(proxyUrl);
+    if (!['http:', 'https:', 'socks5:', 'socks5h:'].includes(url.protocol)
+      || !url.hostname
+      || (!url.port && !['http:', 'https:'].includes(url.protocol))
+      || !['', '/'].includes(url.pathname)
+      || url.search
+      || url.hash) {
+      throw new Error('invalid');
+    }
+  } catch {
+    throw new Error('invalid');
+  }
+  return proxyUrl;
+}