fix(api): 渠道请求头 - 补充自定义 Header 配置并应用到上游请求

Refs #39

web/src/services/api/custom-channel-relay.ts

@@ -1,6 +1,6 @@
-import { isSystemProxyBaseUrl, resolveBackendApiUrl, type AiConfig } from "@/stores/use-config-store";
+import { isSystemProxyBaseUrl, resolveBackendApiUrl, type AiConfig, type ChannelHeader } from "@/stores/use-config-store";
 
-type RelayConfig = Pick<AiConfig, "baseUrl" | "apiKey" | "apiFormat">;
+type RelayConfig = Pick<AiConfig, "baseUrl" | "apiKey" | "apiFormat"> & { headers?: ChannelHeader[] };
 
 export type ChannelRequest = {
     url: string;
@@ -16,13 +16,22 @@ export function channelRequest(config: RelayConfig, upstreamUrl: string, headers
     }
 
     const normalizedUpstreamUrl = new URL(upstreamUrl).toString();
+    normalizedHeaders.delete("X-Canvas-Upstream-Headers");
     normalizedHeaders.delete("x-goog-api-key");
     normalizedHeaders.set("Authorization", `Bearer ${config.apiKey}`);
     normalizedHeaders.set("X-Canvas-Upstream-URL", normalizedUpstreamUrl);
     normalizedHeaders.set("X-Canvas-Upstream-Format", config.apiFormat === "gemini" ? "gemini" : "openai");
+    if (config.headers?.length) normalizedHeaders.set("X-Canvas-Upstream-Headers", encodeChannelHeaders(config.headers));
     return {
         url: resolveBackendApiUrl("/api/ai/custom"),
         headers: Object.fromEntries(normalizedHeaders.entries()),
         credentials: "include",
     };
 }
+
+function encodeChannelHeaders(headers: ChannelHeader[]) {
+    const bytes = new TextEncoder().encode(JSON.stringify(headers));
+    let binary = "";
+    for (const byte of bytes) binary += String.fromCharCode(byte);
+    return btoa(binary);
+}