refactor: update OpenAI TTS integration and cleanup imports

- index.vue: comment out cockpit simulator image
- learn.vue: remove unused imports (useRadioTTS, learnModules)
- atc/say.post.ts & utils/normalize.ts: rename openaiOld → normalize, adjust TTS calls, skip ensureDir/writeFile
- communicationsEngine.ts: fix atcDecisionTree import path

shared/utils/communicationsEngine.ts

@@ -1,6 +1,6 @@
 // composables/communicationsEngine.ts
 import { ref, computed, readonly } from 'vue'
-import atcDecisionTree from "./atcDecisionTree";
+import atcDecisionTree from "../data/atcDecisionTree";
 
 // --- DecisionTree-Types (aus ~/data/atcDecisionTree.json abgeleitet) ---
 type Role = 'pilot' | 'atc' | 'system'