feat(10-redo-C): CRM leads module — schema, services, UI (Phase 10 redo)

Stage C of staged Phase 10 redo. Restores dangling phase10-wip work:
- schema.ts: leads expansion + activities/reminders tables + relations
- lead-service.ts / lead-validators.ts service layer
- /admin/leads list + detail + actions, LeadTable/LeadDetail/LeadForm
- LogActivityModal, SendQuoteModal, FollowUpWidget on dashboard
- migration 0005 (applied to prod DB in Stage B, along with
  previously-missing 0001/0003/0004 — root cause of all post-deploy
  500s: prod DB had no migrations applied since 0000)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/app/admin/leads/[id]/page.tsx

@@ -0,0 +1,16 @@
+import { notFound } from "next/navigation";
+import { getLeadById, getActivityLog, getUpcomingReminders } from "@/lib/lead-service";
+import { LeadDetail } from "@/components/admin/leads/LeadDetail";
+
+export default async function LeadDetailPage({ params }: { params: { id: string } }) {
+  const lead = await getLeadById(params.id);
+
+  if (!lead) {
+    notFound();
+  }
+
+  const activities = await getActivityLog(params.id);
+  const reminders = await getUpcomingReminders(params.id);
+
+  return <LeadDetail lead={lead} activities={activities} reminders={reminders} />;
+}