feat(db): phase 4 group 1 — lib/ settings + notifications to Drizzle

Convert lib/settings.ts, lib/notifications/{in-app,email,capa-escalation,
effectiveness-recheck}.ts from Supabase PostgREST to Drizzle asAdmin queries.
Drop supabase arg from all call sites in app/api/ and cron routes. Rewrite
notification unit tests to mock @/lib/db/with-user instead of SupabaseClient.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/api/incidents/[id]/close/route.ts

@@ -51,7 +51,7 @@ export async function POST(
   })
 
   if (incident.reported_by) {
-    await createInAppNotifications(supabase, [{
+    await createInAppNotifications([{
       userId: incident.reported_by,
       title: `Your incident report ${incident.reference_no ?? ''} has been closed`,
       link: '/reporter',