fix(user): require nuclear delete confirmation first

[aiirvizionz]

Summary

• validate the explicit nuclear-delete confirmation immediately after auth
• avoid service-role user lookups and delete RPC setup when confirmation is missing
• add regression coverage for the no-confirmation path

Test

• node node_modules\vitest\vitest.mjs run --config %TEMP%\qryptchat-vitest-minimal.config.mjs "src/app/api/user/nuclear-delete/route.test.js"
• git diff --check

uGig billable bugfix candidate. Not counted as revenue until accepted, invoiced, and paid.