feat(migrations): finalize email_send_log — drop error column + enable RLS

supabase/migrations/20260630211500_finalize_email_send_log.sql

@@ -0,0 +1,14 @@
+-- Finalize email_send_log (recoupable/chat#1829): drop the unused `error`
+-- column and enable RLS.
+--
+-- `error` (the Resend send-failure reason) shipped in the create migration but
+-- isn't needed for the core observability goal — the empty-email failures
+-- succeed (`success:true`), so it's always null for them, and real send
+-- failures are rare/unobserved. The api writer never populates it.
+--
+-- RLS: enabled with no policies, matching neighboring internal/service-written
+-- tables (error_logs, the playcount store). The api writes via the service role
+-- (which bypasses RLS); anon/authenticated have no access to this internal log.
+
+ALTER TABLE public.email_send_log DROP COLUMN IF EXISTS error;
+ALTER TABLE public.email_send_log ENABLE ROW LEVEL SECURITY;