Admin #346 — Image upload 413s: our own nginx was capping at 1MB, now 32MB

Confirms the diagnosis exactly. A file well under the stated 2MB limit was being rejected by our own infrastructure before it reached the application, which is why the error was a bare HTTP 413 rather than a readable message. At a 32MB ceiling the 5MB application limit is comfortably safe. **Test (Tier 1, minutes):** upload a 4MB image on Culture, Today and the profile avatar. All should succeed.