feat(10-02): lead CRUD UI with list, detail, and form components

- /admin/leads list page with LeadTable component (all leads with status badges)
- /admin/leads/[id] detail page with full lead profile and activity log
- LeadForm component for creating/editing leads (modal dialogs)
- Server actions: createLead, updateLead, deleteLead with Zod validation
- Admin sidebar updated to include Lead link
- Added missing UI dependencies: @radix-ui/react-dialog, date-fns, Form component

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

package.json

@@ -13,6 +13,7 @@
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
     "@hookform/resolvers": "^5.2.2",
+    "@radix-ui/react-dialog": "^1.1.16",
     "@radix-ui/react-label": "^2.1.8",
     "@radix-ui/react-progress": "^1.1.8",
     "@radix-ui/react-select": "^2.2.6",
@@ -21,6 +22,7 @@
     "@radix-ui/react-tabs": "^1.1.13",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "date-fns": "^4.4.0",
     "drizzle-orm": "^0.45.2",
     "lucide-react": "^1.14.0",
     "nanoid": "^5.1.11",