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/route.ts

@@ -165,8 +165,8 @@ async function handlePost(request: Request) {
   // WhatsApp alert — fire-and-forget alongside email
   ;(async () => {
     try {
-      const phoneNumberId = await getApiKey(supabase, 'META_WHATSAPP_PHONE_NUMBER_ID')
-      const accessToken = await getApiKey(supabase, 'META_WHATSAPP_ACCESS_TOKEN')
+      const phoneNumberId = await getApiKey('META_WHATSAPP_PHONE_NUMBER_ID')
+      const accessToken = await getApiKey('META_WHATSAPP_ACCESS_TOKEN')
       const { data: siteData } = await supabase
         .from('sites').select('name').eq('id', zone.site_id).single()
       const siteName = (siteData as { name: string } | null)?.name ?? 'Unknown'
@@ -177,7 +177,6 @@ async function handlePost(request: Request) {
         .eq('site_id', zone.site_id)
 
       await createInAppNotifications(
-        supabase,
         (recipients ?? []).map((r: { id: string }) => ({
           userId: r.id,
           title: `New ${input.incident_type.replace(/_/g, ' ')} incident ${incident.reference_no ?? ''} at ${siteName}`,
@@ -205,7 +204,7 @@ async function handlePost(request: Request) {
   // Embed description asynchronously for future similarity search
   const supabaseForEmbed = supabase
   import('@/lib/settings').then(({ getApiKey }) =>
-    getApiKey(supabaseForEmbed, 'GOOGLE_AI_API_KEY').then(googleAiKey =>
+    getApiKey('GOOGLE_AI_API_KEY').then(googleAiKey =>
       import('@/lib/claude/embed').then(({ embedText }) =>
         embedText(input.description.trim(), googleAiKey).then(embedding =>
           supabase.from('incidents').update({