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

frontend/src/components/ai/AiAlertBanner.tsx

@@ -8,12 +8,13 @@ export default function AiAlertBanner() {
   const [dismissedIds, setDismissedIds] = useState<Set<string>>(() => new Set());
   const [errorDismissed, setErrorDismissed] = useState(false);
 
-  const { data: alerts, isLoading, isError, error } = useQuery({
+  const { data: resp, isLoading, isError, error } = useQuery({
     queryKey: ["ai", "alerts"],
     queryFn: () => analyticsService.getAlerts(),
   });
 
-  const visible = alerts?.filter((a) => !dismissedIds.has(a.id)) ?? [];
+  const alerts = resp?.alerts ?? [];
+  const visible = alerts.filter((a, i) => !dismissedIds.has(String(i)));
 
   if (isLoading) {
     return (
@@ -43,7 +44,7 @@ export default function AiAlertBanner() {
 
   if (isError && errorDismissed) return null;
 
-  if (!alerts?.length) {
+  if (!alerts.length) {
     return (
       <div className="rounded-lg border border-muted bg-muted/20 p-4 flex items-start gap-3">
         <Sparkles className="h-5 w-5 text-muted-foreground shrink-0 mt-0.5" />
@@ -56,8 +57,8 @@ export default function AiAlertBanner() {
 
   return (
     <div className="space-y-3">
-      {visible.map((alert) => (
-        <div key={alert.id} className="rounded-lg border border-warning/30 bg-warning/10 p-4 flex items-start gap-3">
+      {visible.map((alert, idx) => (
+        <div key={idx} className="rounded-lg border border-warning/30 bg-warning/10 p-4 flex items-start gap-3">
           <AlertTriangle className="h-5 w-5 text-warning shrink-0 mt-0.5" />
           <div className="flex-1">
             <p className="text-sm font-medium flex items-center gap-1">
@@ -69,7 +70,7 @@ export default function AiAlertBanner() {
             variant="ghost"
             size="icon"
             className="h-7 w-7 shrink-0"
-            onClick={() => setDismissedIds((prev) => new Set(prev).add(alert.id))}
+            onClick={() => setDismissedIds((prev) => new Set(prev).add(String(idx)))}
           >
             <X className="h-4 w-4" />
           </Button>