I need a compact FastAPI micro-service that will sit between my desktop application and a remote endpoint. Workflow 1. My desktop app posts an XML file from the local machine to your FastAPI endpoint. 2. Your service signs that XML with the .p12 certificate I supply, then inserts the required QR code. 3. It forwards the signed file to the target URL I will provide. 4. Whatever the remote server returns comes back as JSON; simply pass that JSON straight through to the original caller. Technical notes • Target stack: Python 3.x, FastAPI, async/await. Feel free to use cryptography, PyOpenSSL, or any reliable library for handling the .p12 signature, and qrcode or similar for QR generation. • Please handle the certificate in memory only and remove any temp artifacts after use. • No GUI is needed—just a clean REST endpoint and clear logging. Deliverables • FastAPI app exposing a POST /process (or comparable) route. • Working PFX/P12 signing routine and QR code insertion into the XML payload. • Async HTTP forwarder that returns the untouched JSON response from the external service. • README with setup steps, environment variables, and a quick curl example. • Minimal unit test proving the full happy-path workflow. Acceptance criteria: I will send a sample XML; a successful round trip—signed XML containing the QR code and the correct JSON response echoed back—will mark the job complete. Let me know your estimated turnaround and any dependencies you prefer so we can get started immediately.