feat: Generation Page AI workflows + AI/Vector modules + exam session fixes

Generation Page (complete rebuild):
- Full production-parity exam generation wizard with 4 IELTS modules
- Reading: AI passage gen, 5 exercise types (MCQ, Fill, Write, T/F, Match)
- Listening: 4 section types, AI context gen, TTS audio gen (ElevenLabs)
- Writing: Task 1/2, AI instruction gen, word limits, marks
- Speaking: 3 parts, AI script gen, avatar video gen (7 avatars)
- Per-module config: timer, CEFR difficulty, access, approval, rubrics
- Exam submission workflow (draft/published)

Exam Structures:
- New encoach.exam.structure model + CRUD controller
- ExamStructuresPage wired to real API

AI Module (encoach_ai):
- OpenAI service, ElevenLabs TTS, AWS Polly, ELAI avatars
- AI settings model with Odoo config parameters
- 7 generation endpoints (passage, exercises, instructions, scripts, context)

Vector Module (encoach_vector):
- pgvector integration for RAG-based content search
- Embedding service with sentence-transformers

Exam Session Fixes:
- Fixed ExamSession.tsx field mapping (question_type→type, exam_title→title)
- Fixed submit payload to include attempt_id and answers
- Fixed normalizeType to handle null/undefined

Tested: 12/12 API tests passed, browser-verified with real OpenAI calls
Made-with: Cursor

src/pages/PaymentRecordPage.tsx

@@ -52,7 +52,7 @@ export default function PaymentRecordPage() {
         </div>
       </div>
 
-      <AiTipBanner tip="PAY-003 (Tech Co) is unpaid and overdue. PMB-1004 failed — AI recommends sending an automated retry notification to Emma Brown." variant="recommendation" />
+      <AiTipBanner context="payment-record" variant="recommendation" />
 
       <Tabs defaultValue="payments">
         <TabsList>
@@ -61,7 +61,7 @@ export default function PaymentRecordPage() {
         </TabsList>
 
         <TabsContent value="payments" className="mt-4 space-y-4">
-          <AiReportNarrative narrative="Total revenue collected: $13,500 from 2 corporate payments. One commission of $2,000 remains unpaid. Collection rate: 67%. Trend: Q1 payments are on track but Tech Co requires follow-up." />
+          <AiReportNarrative report_type="payments" data={{ payments }} />
           <Card className="border-0 shadow-sm">
             <CardContent className="p-0">
               <Table>