Werkzeug's HTTPExceptions subclass Exception, so the catch-all handler
saw them too and turned every 405, 400, 413 and 415 into a 500
UNKNOWN_ERROR. A GET on a POST-only route answered "an error occurred;
see logs for details", which tells the caller nothing and blames the
wrong side -- found while probing a device whose POST-only config
endpoints did exactly that.
Hand HTTPExceptions back as themselves, with their own status and
description. A genuine server fault still reports as one, with the
detail this branch adds.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5
