feat: member portal Sprint 10 — Knowledge Base

- KnowledgeBoard + KnowledgeItem models + migration (DRAFT/PUBLISHED/ARCHIVED status, slug per tenant)
- KnowledgeModule: admin CRUD for boards + items (auto-slug, status workflow)
- Member endpoint GET /my/knowledge?q= — published items grouped by board, optional text search over question/answer
- /my/knowledge page: search box + collapsible boards with accordion FAQ items
- KnowledgeItem accordion + KnowledgeSearch (debounced URL-driven) client components
- Knowledge nav item; register KnowledgeModule

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

apps/web/app/my/layout.tsx

@@ -5,6 +5,7 @@ import { redirect } from 'next/navigation';
 const NAV = [
   { href: '/my', label: 'Dashboard' },
   { href: '/my/ask', label: 'Ask AI' },
+  { href: '/my/knowledge', label: 'Knowledge' },
   { href: '/my/digest', label: 'Digest' },
   { href: '/my/events', label: 'Events' },
   { href: '/my/seva', label: 'Seva & Points' },