Add thread audit replay controls

AgentCompany-New/src/main/database/migrations/019-audit-replay.ts

@@ -0,0 +1,18 @@
+export const auditReplaySchema = `
+  create table if not exists audit_replay_runs (
+    id text primary key,
+    org_id text not null references organizations(id) on delete cascade,
+    thread_id text not null references chat_threads(id) on delete cascade,
+    event_count integer not null,
+    event_digest text not null,
+    replay_json text not null,
+    created_by_employee_id text references employees(id) on delete set null,
+    created_at text not null
+  );
+
+  create index if not exists idx_audit_replay_runs_org_created on audit_replay_runs(org_id, created_at);
+  create index if not exists idx_audit_replay_runs_thread on audit_replay_runs(thread_id, created_at);
+
+  insert into schema_migrations(version, name, applied_at)
+  values (19, 'audit_replay', datetime('now'));
+`;