feat: improve discord webhook configuration flexibility and add error logging for failed requests

apps/backend/src/routes/post.ts

@@ -68,11 +68,16 @@ async function sendDiscordNotification(payload: {
     tags: string[];
     imageUrl?: string;
 }) {
-    const webhookUrl = config.discord.webhook;
+    const webhookUrl = (config as any)?.webhook?.discord_webhook_uri
-    if (!webhookUrl) return;
+        ?? (config as any)?.discord?.webhook;
+
+    if (!webhookUrl || typeof webhookUrl !== "string") {
+        console.warn("[Discord Webhook] missing webhook URL in config.toml (expected [webhook].discord_webhook_uri)");
+        return;
+    }
 
     try {
-        await fetch(webhookUrl, {
+        const response = await fetch(webhookUrl, {
             method: "POST",
             headers: { "Content-Type": "application/json" },
             body: JSON.stringify({
@@ -86,6 +91,11 @@ async function sendDiscordNotification(payload: {
                 }],
             }),
         });
+
+        if (!response.ok) {
+            const errorText = await response.text().catch(() => "");
+            console.error(`[Discord Webhook] failed status=${response.status} body=${errorText}`);
+        }
     } catch (error) {
         console.error("[Discord Webhook Error]", error);
     }