feat(classroom): integrate user feedback — audio speed, METAR TTS, phonetics, UI fixes

- Lower default audio speed to 0.85x, extend slider range to 0.5-1.3x
- Add METAR normalization for intelligible TTS (wind, vis, clouds, temp, QNH)
- Expand SID/STAR suffix regex to handle spaces (SUGOL 2S)
- Add approach suffix phonetic expansion (ILS 08R Y → Yankee)
- Fix "Soll:" → "Expected:" in readback feedback
- Accept numeric values for pushback delay field
- Add news article documenting the changes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/learn/config.ts

@@ -25,7 +25,7 @@ export const LEARN_CONFIG_DEFAULTS: LearnConfig = {
   radioLevel: 5,
   voice: '',
   audioChallenge: true,
-  audioSpeed: 1,
+  audioSpeed: 0.85,
 }
 
 export function createDefaultLearnConfig(): LearnConfig {