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/AiInsightsPanel.tsx

@@ -1,32 +1,31 @@
 import { useEffect, useMemo } from "react";
 import { useMutation } from "@tanstack/react-query";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
-import { Sparkles, TrendingUp, AlertTriangle, Trophy, Loader2 } from "lucide-react";
-import { analyticsService } from "@/services/analytics.service";
-import type { AiInsight } from "@/types";
+import { Sparkles, TrendingUp, AlertTriangle, Info, Loader2 } from "lucide-react";
+import { analyticsService, type AiInsightItem } from "@/services/analytics.service";
 import { useToast } from "@/hooks/use-toast";
 
 const EMPTY_PAYLOAD: Record<string, unknown> = {};
 
-function insightIcon(type: AiInsight["type"]) {
-  switch (type) {
-    case "positive":
-      return Trophy;
-    case "warning":
+function insightIcon(severity: AiInsightItem["severity"]) {
+  switch (severity) {
+    case "critical":
       return AlertTriangle;
-    default:
+    case "warning":
       return TrendingUp;
+    default:
+      return Info;
   }
 }
 
-function insightColor(type: AiInsight["type"]) {
-  switch (type) {
-    case "positive":
-      return "text-primary";
+function insightColor(severity: AiInsightItem["severity"]) {
+  switch (severity) {
+    case "critical":
+      return "text-destructive";
     case "warning":
       return "text-warning";
     default:
-      return "text-success";
+      return "text-primary";
   }
 }
 
@@ -51,10 +50,10 @@ export default function AiInsightsPanel({ data = EMPTY_PAYLOAD }: Props) {
 
   useEffect(() => {
     mutation.mutate(data);
-    // eslint-disable-next-line react-hooks/exhaustive-deps -- refetch when serialized payload changes
+    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [payloadKey]);
 
-  const items = mutation.data ?? [];
+  const items = mutation.data?.insights ?? [];
 
   return (
     <Card className="border-0 shadow-sm">
@@ -79,19 +78,19 @@ export default function AiInsightsPanel({ data = EMPTY_PAYLOAD }: Props) {
         )}
         {!mutation.isPending && items.length > 0 && (
           <div className="grid grid-cols-1 md:grid-cols-3 gap-4">
-            {items.map((item) => {
-              const Icon = insightIcon(item.type);
-              const color = insightColor(item.type);
+            {items.map((item, idx) => {
+              const Icon = insightIcon(item.severity);
+              const color = insightColor(item.severity);
               return (
-                <div key={item.id} className="rounded-lg border bg-muted/30 p-4">
+                <div key={idx} className="rounded-lg border bg-muted/30 p-4">
                   <div className="flex items-center gap-2 mb-2">
                     <Icon className={`h-4 w-4 ${color}`} />
                     <span className="text-sm font-semibold">{item.title}</span>
                   </div>
                   <p className="text-sm text-muted-foreground">{item.description}</p>
-                  {item.metric != null && item.value != null && (
-                    <p className="text-xs text-muted-foreground mt-2">
-                      {item.metric}: {item.value}
+                  {item.recommendation && (
+                    <p className="text-xs text-muted-foreground mt-2 italic">
+                      {item.recommendation}
                     </p>
                   )}
                 </div>