Audit findings from MARS-574 retro review: 4 BLOCKs to fix

audit-mars-ca cold review of MARS-574 backlog found 4 real defects: a589ff2/cf6e422 (MARS-565 email-send, live recipient lookup includes soft-deleted users, missing no-live warning, null-only selection can suppress valid snapshot address = false send success, Class-A path); ada40ad (subreport drill loses active scope vs count); 3f23b0b (orange text contrast 3.19:1 below 4.5:1); 0d4bfb3 (toast shows persisted tooth number not current selection). Coder-mars-cc has findings direct from audit, fixing now.