Debug Boom Endpoint

Fail on purpose, to exercise the error masking and reporting flow end to end.

Two shapes, because they take different paths through auxiliary/error_handlers.py: ?kind=unhandled a bare exception escaping the endpoint ?kind=leak a 500 whose detail contains real infrastructure strings, which is what 113 sites in this codebase actually do

Both must come back as a generic message plus a reference, with the real text only in CloudWatch. SUPER_ADMIN only, and it refuses outright when APP_ENV=prod — a working "make the server fail" endpoint has no business existing in production.