075b45f020
Closes #574. Reporter (@blazmaric) identified the root cause cleanly: express-validator's `.normalizeEmail()` applies provider-specific canonicalization by default — Gmail dot-stripping, +tag stripping, googlemail → gmail folding, etc. That's wrong for identity: PicPeak uses email as a login identifier, so `john.doe@gmail.com` getting silently stored as `johndoe@gmail.com` means the user can't log in with the address they were invited with. The bug existed at 17 call sites across the codebase (auth, admin user create/update, customer create/update, event create/update on three different routes, customer login, feedback submission). All of them are identity-bearing — none had a legitimate reason to strip dots for deduplication. Fix: introduce one shared options object in `utils/emailNormalization` disabling every provider-specific normalization (gmail_remove_dots, gmail_remove_subaddress, gmail_convert_googlemaildotcom, outlookdotcom_remove_subaddress, yahoo_remove_subaddress, icloud_remove_subaddress). The only default left enabled is `all_lowercase`, which is safe — local-parts are case-insensitive in practice on every major provider, and lowercasing keeps login lookup consistent. Every call site updated to pass the shared options. 7 unit tests pin the preserved-dots, preserved-subaddress, preserved-googlemail-domain, and still-lowercase behaviours so a future refactor can't silently regress. ## Migration note Existing accounts whose emails were already stripped before this fix remain with the stripped form in the DB. The fix takes effect for new invitations going forward. If an admin re-invites an existing user with the un-stripped address, that would create a duplicate account — out of scope here; if it becomes a real problem we can add a backward-compat login fallback (try lookup with dot-stripped form too) as a separate change.