feat: Add OCR Processing Layers Viewer UI and log proxy middleware

backend/pfm-web-app/src/app/api/documents/[id]/logs/route.ts

@@ -0,0 +1,37 @@
+import { NextRequest, NextResponse } from "next/server";
+import { query } from "../../../../../db";
+
+export const dynamic = "force-dynamic";
+
+export async function GET(
+  req: NextRequest,
+  { params }: { params: Promise<{ id: string }> | { id: string } }
+) {
+  try {
+    // Handle both Promise and synchronous params for Next.js version compatibility
+    const resolvedParams = await params;
+    const { id } = resolvedParams;
+    const docId = parseInt(id, 10);
+    
+    if (isNaN(docId)) {
+      return NextResponse.json({ error: "Invalid document ID" }, { status: 400 });
+    }
+
+    const res = await query(
+      "SELECT filename, processing_logs FROM documents WHERE id = $1",
+      [docId]
+    );
+
+    if (res.rowCount === 0 || !res.rows[0]) {
+      return NextResponse.json({ error: "Document not found" }, { status: 404 });
+    }
+
+    return NextResponse.json({
+      filename: res.rows[0].filename,
+      processing_logs: res.rows[0].processing_logs || null
+    });
+  } catch (error: any) {
+    console.error("Error fetching document logs:", error);
+    return NextResponse.json({ error: error.message }, { status: 500 });
+  }
+}