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/api/prisma/schema.prisma

@@ -96,6 +96,8 @@ model Tenant {
   gamificationEvents GamificationEvent[]
   circles            Circle[]
   askAIQueries       AskAIQuery[]
+  knowledgeBoards    KnowledgeBoard[]
+  knowledgeItems     KnowledgeItem[]
 }
 
 enum AdminRole {
@@ -751,3 +753,49 @@ model AskAIQuery {
   @@index([tenantId, createdAt])
   @@index([userId, createdAt])
 }
+
+// ============================================================================
+// Knowledge Base (admin-curated FAQ boards)
+// ============================================================================
+
+enum KnowledgeItemStatus {
+  DRAFT
+  PUBLISHED
+  ARCHIVED
+}
+
+model KnowledgeBoard {
+  id          String   @id @default(cuid())
+  tenantId    String
+  tenant      Tenant   @relation(fields: [tenantId], references: [id])
+  name        String
+  description String?
+  slug        String
+  sortOrder   Int      @default(0)
+  createdAt   DateTime @default(now())
+  updatedAt   DateTime @updatedAt
+
+  items KnowledgeItem[]
+
+  @@unique([tenantId, slug])
+  @@index([tenantId])
+}
+
+model KnowledgeItem {
+  id        String              @id @default(cuid())
+  boardId   String
+  board     KnowledgeBoard      @relation(fields: [boardId], references: [id], onDelete: Cascade)
+  tenantId  String
+  tenant    Tenant              @relation(fields: [tenantId], references: [id])
+  question  String
+  answer    String
+  tags      String[]
+  status    KnowledgeItemStatus @default(DRAFT)
+  sortOrder Int                 @default(0)
+  createdBy String
+  createdAt DateTime            @default(now())
+  updatedAt DateTime            @updatedAt
+
+  @@index([tenantId, status])
+  @@index([boardId, status])
+}