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/AiGeneratorModal.tsx

@@ -40,8 +40,9 @@ export default function AiGeneratorModal() {
         difficulty,
         count,
       }),
-    onSuccess: (res) => {
-      setLocalExercises(Array.isArray(res.exercises) ? res.exercises : []);
+    onSuccess: (res: Record<string, unknown>) => {
+      const items = Array.isArray(res.questions) ? res.questions : Array.isArray(res.exercises) ? res.exercises : [];
+      setLocalExercises(items);
     },
     onError: (err: Error) => {
       toast({
@@ -57,6 +58,21 @@ export default function AiGeneratorModal() {
     generateMutation.mutate();
   };
 
+  const saveMutation = useMutation({
+    mutationFn: () => generationService.saveGenerated(moduleType, localExercises ?? []),
+    onSuccess: (res) => {
+      toast({ title: "Saved", description: `${res.saved} assignments saved successfully.` });
+      setOpen(false);
+    },
+    onError: (err: Error) => {
+      toast({
+        variant: "destructive",
+        title: "Save failed",
+        description: err.message || "Could not save generated assignments.",
+      });
+    },
+  });
+
   const generated = localExercises;
 
   const handleRemove = (index: number) => {
@@ -188,7 +204,17 @@ export default function AiGeneratorModal() {
               );
             })}
             <div className="flex gap-2">
-              <Button className="flex-1">Save All</Button>
+              <Button
+                className="flex-1"
+                onClick={() => saveMutation.mutate()}
+                disabled={saveMutation.isPending || !generated?.length}
+              >
+                {saveMutation.isPending ? (
+                  <><Loader2 className="h-4 w-4 mr-2 animate-spin" /> Saving...</>
+                ) : (
+                  "Save All"
+                )}
+              </Button>
               <Button
                 variant="outline"
                 onClick={() => {