fix(t1-live): remove questionnaire dependency from T1 Live session

- buildT1SystemPrompt() now static (no reponses param); examiner
  formulates questions from what it hears in real-time audio stream
- Remove context guard + close 4004 CONTEXT_MISSING; Gemini session
  opens immediately after auth (aligns with T2 flow)
- Remove parseT1Context, validateReponses import from route
- Unknown WS message types silently ignored (debug log + return)
- Update Prompt_t1live.md and CHANGELOG-backend
- Tests: 309/309 green

src/routes/__tests__/t1live.test.ts

@@ -33,7 +33,7 @@ vi.mock("../../lib/geminiPhonology", () => ({
 
 import { supabase } from "../../lib/supabase";
 import { correctEO as deepseekCorrectEO } from "../../lib/deepseek";
-import { parseT1Context, runT1LiveCorrection } from "../t1live";
+import { runT1LiveCorrection } from "../t1live";
 import type { WebSocketLike } from "../../lib/geminiLive";
 
 // ─── Helpers ─────────────────────────────────────────────────────────────────
@@ -87,14 +87,6 @@ function mockProductionUpdate(errorMsg: string | null = null) {
   } as any);
 }
 
-const REPONSES = {
-  prenom_age_ville: "Hermann, 35 ans, Lyon",
-  formation_metier: "ingénieur en informatique",
-  situation_familiale: "marié, deux enfants",
-  loisirs: "la randonnée et la photographie",
-  motivation_canada: "de meilleures opportunités professionnelles",
-};
-
 const FAKE_RAPPORT = {
   score: 14,
   nclc: 8,
@@ -108,34 +100,6 @@ const FAKE_RAPPORT = {
 
 // ─── Tests ───────────────────────────────────────────────────────────────────
 
-describe("parseT1Context", () => {
-  it("accepte un message {type:'context', reponses} valide", () => {
-    const result = parseT1Context(
-      JSON.stringify({ type: "context", reponses: REPONSES }),
-    );
-    expect(result).toEqual({ ok: true, reponses: REPONSES });
-  });
-
-  it("refuse un message sans type 'context'", () => {
-    const result = parseT1Context(
-      JSON.stringify({ type: "audio", data: "AAAA" }),
-    );
-    expect(result).toEqual({ ok: false });
-  });
-
-  it("refuse un contexte aux réponses invalides (champ manquant)", () => {
-    const { motivation_canada: _omit, ...partiel } = REPONSES;
-    const result = parseT1Context(
-      JSON.stringify({ type: "context", reponses: partiel }),
-    );
-    expect(result).toEqual({ ok: false });
-  });
-
-  it("refuse un payload non-JSON", () => {
-    expect(parseT1Context("pas du json {")).toEqual({ ok: false });
-  });
-});
-
 describe("runT1LiveCorrection", () => {
   beforeEach(() => {
     vi.clearAllMocks();