Sub-ticket of VENUS-64 Support-thread enrichment (Mars-parity, Elazar 'A in both' ratified): P0 shared email leg, P1 DDL (supportTicketMessages+view+ticketNumber+assignedAgent+urlPath/userAgent cols), P2 server actions, P3 admin thread UI, P4 user /soporte/[id]. Ref: mars src/lib/support-thread.ts. Two-way thread + reply-emails-student · venus