Introduces a Redis-backed sliding-window rate limiter for upload
endpoints (/api/ui-upload, /api/process-url) that:
- Enforces per-user limits (default: 20 uploads / 60 s)
- Dynamically reduces limits under system stress (queue depth, CPU load)
- Returns 429 with Retry-After header when exceeded
- Fails open when Redis is unavailable
- Works with the existing client-side adaptive back-off
Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
copilot-swe-agent[bot]