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/AiSearchBar.tsx

@@ -27,7 +27,7 @@ export default function AiSearchBar() {
     searchMutation.mutate(query.trim());
   };
 
-  const results = searchMutation.data;
+  const result = searchMutation.data;
 
   return (
     <div className="relative max-w-md w-full">
@@ -57,35 +57,43 @@ export default function AiSearchBar() {
         )}
       </div>
 
-      {(searchMutation.isPending || results !== undefined) && (
+      {(searchMutation.isPending || result !== undefined) && (
         <div className="absolute top-full mt-1 left-0 right-0 z-50 rounded-lg border bg-popover p-3 shadow-md">
           {searchMutation.isPending ? (
             <div className="flex items-center gap-2 text-sm text-muted-foreground">
               <Loader2 className="h-4 w-4 animate-spin text-primary" />
               AI is searching...
             </div>
-          ) : results && results.length > 0 ? (
+          ) : result?.answer ? (
             <div className="text-sm space-y-2 max-h-64 overflow-y-auto">
-              {results.map((r, i) => (
-                <div
-                  key={`${r.title}-${i}`}
-                  className="flex items-start gap-2 border-b border-border/60 pb-2 last:border-0 last:pb-0"
-                >
-                  <Sparkles className="h-4 w-4 text-primary shrink-0 mt-0.5" />
-                  <div className="min-w-0">
-                    <p className="font-medium">{r.title}</p>
-                    <p className="text-muted-foreground text-xs mt-0.5">{r.description}</p>
-                    {r.url && (
-                      <button
-                        type="button"
-                        className="text-xs text-primary mt-1 hover:underline"
-                        onClick={() => navigate(r.url!)}
-                      >
-                        Go to {r.url}
-                      </button>
-                    )}
-                  </div>
+              <div className="flex items-start gap-2 pb-2">
+                <Sparkles className="h-4 w-4 text-primary shrink-0 mt-0.5" />
+                <p className="text-muted-foreground">{result.answer}</p>
+              </div>
+              {result.suggestions?.length > 0 && (
+                <div className="border-t pt-2 space-y-1">
+                  <p className="text-xs font-semibold text-primary">Related queries</p>
+                  {result.suggestions.map((s, i) => (
+                    <button
+                      key={i}
+                      type="button"
+                      className="block text-xs text-primary hover:underline"
+                      onClick={() => { setQuery(s); searchMutation.mutate(s); }}
+                    >
+                      {s}
+                    </button>
+                  ))}
                 </div>
+              )}
+              {result.related_actions?.map((a, i) => (
+                <button
+                  key={i}
+                  type="button"
+                  className="text-xs text-primary hover:underline"
+                  onClick={() => navigate(a.action)}
+                >
+                  {a.label}
+                </button>
               ))}
             </div>
           ) : (