Address classroom tester feedback (Detlef / FSC e.V.)

Fixes the most impactful issues from ~1.5h of testing:

- TTS: spell SID prefixes phonetically (ANEKI → Alfa November Echo Kilo
  India) so unfamiliar waypoint names are intelligible without prior
  briefing context.
- TTS: expand standalone uppercase waypoints after via/direct (with a
  skip list for common ATC English tokens like MAYDAY, CLEARED, …).
- TTS: join taxi route tokens with ", " so pauses land between
  taxiways (C5, Z5, U10, …) instead of running together.
- TTS: handle "ILS Z 25C" variant before the runway → "ILS Zulu runway
  two five center" (was previously read as "Zee twentyfive cee").
- Scenarios: derive arrivalRunway from the chosen approach so the
  controller no longer clears a flight for ILS 25C onto runway 18.
- Radio check: accept any readability 1–5 (numeric or spoken), shorten
  placeholder so it fits the sm-width field.
- Line-up readback: clearer hint about the runway-first ICAO order.
- Classroom UI: disable browser autocomplete/autocorrect on readback
  inputs (Edge autofill was injecting unrelated values).
- Classroom UI: "Speak answer" button replays the expected readback as
  TTS so students can hear the correct phrasing.

Tests adjusted for the new SID and taxi-route phonetics.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/pages/classroom.vue

@@ -1077,6 +1077,10 @@
                             :placeholder="fieldPlaceholder(segment.key)"
                             :inputmode="fieldInputmode(segment.key)"
                             :ref="el => assignReadbackFieldRef(segment.key, el as HTMLInputElement | null)"
+                            autocomplete="off"
+                            autocorrect="off"
+                            autocapitalize="none"
+                            spellcheck="false"
                         />
                         <v-icon v-if="fieldPass(segment.key)" size="16" class="blank-status ok">mdi-check</v-icon>
                         <v-icon v-else-if="fieldHasAnswer(segment.key)" size="16" class="blank-status warn">mdi-alert
@@ -1101,6 +1105,17 @@
                     <v-icon size="18">mdi-auto-fix</v-icon>
                     Auto-fill
                   </button>
+                  <button
+                      v-if="correctReadbackText"
+                      class="btn ghost"
+                      type="button"
+                      :disabled="ttsLoading"
+                      @click="speakCorrectReadback"
+                      title="Speak correct readback"
+                  >
+                    <v-icon size="18">mdi-volume-high</v-icon>
+                    Speak answer
+                  </button>
                 </div>
                 <div v-if="result" class="score">
                   <div class="score-num">{{ result.score }}%</div>
@@ -3351,6 +3366,22 @@ const targetPhrase = computed(() => {
   if (!activeLesson.value || !scenario.value) return ''
   return displayCallsign(activeLesson.value.phrase(scenario.value), scenario.value)
 })
+
+const correctReadbackText = computed(() => {
+  if (!activeLesson.value || !scenario.value) return ''
+  return activeLesson.value.readback.map(seg => {
+    if (seg.type === 'text') return typeof seg.text === 'function' ? seg.text(scenario.value!) : seg.text
+    const field = activeLesson.value!.fields.find(f => f.key === seg.key)
+    return field ? field.expected(scenario.value!) : ''
+  }).join('').trim()
+})
+
+async function speakCorrectReadback() {
+  const text = correctReadbackText.value
+  if (!text || ttsLoading.value) return
+  await say(text)
+}
+
 const lessonInfo = computed(() => (activeLesson.value && scenario.value ? activeLesson.value.info(scenario.value) : []))
 
 const lessonReference = computed(() => {