feat: member portal Sprint 9 — Ask AI (RAG over message archive)

- AskAIQuery model + migration (logs question/answer/citations per member)
- AskAIService: RAG pipeline — retrieve via tenant-isolated SearchService (Meili),
  ground LLM in top-8 snippets with inline [n] citations, degrade gracefully when
  OPENROUTER_API_KEY absent or no context (snippet fallback)
- Shared api/common/llm-client.ts (mirrors worker's OpenRouter client)
- SearchModule now exports SearchService
- Member endpoints: GET/POST /my/ask (history + ask)
- /my/ask page + AskChat client component: question box, answer cards with sources
- Ask AI nav item (top of member nav)

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

apps/api/prisma/schema.prisma

@@ -95,6 +95,7 @@ model Tenant {
   sevaOpportunities  SevaOpportunity[]
   gamificationEvents GamificationEvent[]
   circles            Circle[]
+  askAIQueries       AskAIQuery[]
 }
 
 enum AdminRole {
@@ -422,6 +423,7 @@ model TowerUser {
   sevaEntries        SevaEntry[]
   gamificationEvents GamificationEvent[]
   circleMemberships  CircleMembership[]
+  askAIQueries       AskAIQuery[]
 
   @@unique([tenantId, phoneHash])
   @@index([phoneHash])
@@ -730,3 +732,22 @@ model CircleMembership {
   @@unique([circleId, userId])
   @@index([userId])
 }
+
+// ============================================================================
+// Ask AI (RAG over the message archive)
+// ============================================================================
+
+model AskAIQuery {
+  id        String   @id @default(cuid())
+  tenantId  String
+  tenant    Tenant   @relation(fields: [tenantId], references: [id])
+  userId    String
+  user      TowerUser @relation(fields: [userId], references: [id])
+  question  String
+  answer    String
+  citations Json     @default("[]")
+  createdAt DateTime @default(now())
+
+  @@index([tenantId, createdAt])
+  @@index([userId, createdAt])
+}