feat: Add Hardcover currently reading integration with i18n support

- Add CurrentlyReading component with beautiful design
- Integrate into About section
- Add German and English translations
- Add n8n API route for Hardcover integration
- Add comprehensive documentation for n8n setup

app/api/n8n/hardcover/currently-reading/route.ts

@@ -0,0 +1,131 @@
+// app/api/n8n/hardcover/currently-reading/route.ts
+import { NextRequest, NextResponse } from "next/server";
+
+// Cache für 5 Minuten, damit wir n8n nicht zuspammen
+// Hardcover-Daten ändern sich nicht so häufig
+export const revalidate = 300;
+
+export async function GET(request: NextRequest) {
+  // Rate limiting for n8n hardcover endpoint
+  const ip =
+    request.headers.get("x-forwarded-for") ||
+    request.headers.get("x-real-ip") ||
+    "unknown";
+  const ua = request.headers.get("user-agent") || "unknown";
+  const { checkRateLimit } = await import('@/lib/auth');
+  
+  // In dev, many requests can share ip=unknown; use UA to avoid a shared bucket.
+  const rateKey =
+    process.env.NODE_ENV === "development" && ip === "unknown"
+      ? `ua:${ua.slice(0, 120)}`
+      : ip;
+  const maxPerMinute = process.env.NODE_ENV === "development" ? 60 : 10;
+
+  if (!checkRateLimit(rateKey, maxPerMinute, 60000)) { // requests per minute
+    return NextResponse.json(
+      { error: 'Rate limit exceeded. Please try again later.' },
+      { status: 429 }
+    );
+  }
+
+  try {
+    // Check if n8n webhook URL is configured
+    const n8nWebhookUrl = process.env.N8N_WEBHOOK_URL;
+    
+    if (!n8nWebhookUrl) {
+      console.warn("N8N_WEBHOOK_URL not configured for hardcover endpoint");
+      // Return fallback if n8n is not configured
+      return NextResponse.json({
+        currentlyReading: null,
+      });
+    }
+
+    // Rufe den n8n Webhook auf
+    // Add timestamp to query to bypass Cloudflare cache
+    const webhookUrl = `${n8nWebhookUrl}/webhook/hardcover/currently-reading?t=${Date.now()}`;
+    console.log(`Fetching currently reading from: ${webhookUrl}`);
+
+    // Add timeout to prevent hanging requests
+    const controller = new AbortController();
+    const timeoutId = setTimeout(() => controller.abort(), 10000); // 10 second timeout
+
+    try {
+      const res = await fetch(webhookUrl, {
+        method: "GET",
+        headers: {
+          Accept: "application/json",
+          ...(process.env.N8N_SECRET_TOKEN && {
+            Authorization: `Bearer ${process.env.N8N_SECRET_TOKEN}`,
+          }),
+          ...(process.env.N8N_API_KEY && {
+            "X-API-Key": process.env.N8N_API_KEY,
+          }),
+        },
+        next: { revalidate: 300 },
+        signal: controller.signal,
+      });
+
+      clearTimeout(timeoutId);
+
+      if (!res.ok) {
+        const errorText = await res.text().catch(() => 'Unknown error');
+        console.error(`n8n hardcover webhook failed: ${res.status}`, errorText);
+        throw new Error(`n8n error: ${res.status} - ${errorText}`);
+      }
+
+      const raw = await res.text().catch(() => "");
+      if (!raw || !raw.trim()) {
+        throw new Error("Empty response body received from n8n");
+      }
+
+      let data: unknown;
+      try {
+        data = JSON.parse(raw);
+      } catch (parseError) {
+        // Sometimes upstream sends HTML or a partial response; include a snippet for debugging.
+        const snippet = raw.slice(0, 240);
+        throw new Error(
+          `Invalid JSON from n8n (${res.status}): ${snippet}${raw.length > 240 ? "…" : ""}`,
+        );
+      }
+
+      // n8n gibt oft ein Array zurück: [{...}]. Wir wollen nur das Objekt.
+      const readingData = Array.isArray(data) ? data[0] : data;
+
+      // Safety check: if readingData is still undefined/null (e.g. empty array), use fallback
+      if (!readingData) {
+        throw new Error("Empty data received from n8n");
+      }
+
+      // Ensure currentlyReading has proper structure
+      if (readingData.currentlyReading && typeof readingData.currentlyReading === "object") {
+        // Already properly formatted from n8n
+      } else if (readingData.currentlyReading === null || readingData.currentlyReading === undefined) {
+        // No reading data - keep as null
+        readingData.currentlyReading = null;
+      }
+
+      return NextResponse.json(readingData);
+    } catch (fetchError: unknown) {
+      clearTimeout(timeoutId);
+      
+      if (fetchError instanceof Error && fetchError.name === 'AbortError') {
+        console.error("n8n hardcover webhook request timed out");
+      } else {
+        console.error("n8n hardcover webhook fetch error:", fetchError);
+      }
+      throw fetchError;
+    }
+  } catch (error: unknown) {
+    console.error("Error fetching n8n hardcover data:", error);
+    console.error("Error details:", {
+      message: error instanceof Error ? error.message : String(error),
+      stack: error instanceof Error ? error.stack : undefined,
+      n8nUrl: process.env.N8N_WEBHOOK_URL ? 'configured' : 'missing',
+    });
+    // Leeres Fallback-Objekt, damit die Seite nicht abstürzt
+    return NextResponse.json({
+      currentlyReading: null,
+    });
+  }
+}