feat(transcribe): English UI default, language switcher (NO/UK/PL), fix 504 timeout

- Default UI language to English; lang switcher (EN/NO/UK/PL) persisted in localStorage
- Rename 'rettssak/tingrett' preset to 'Mediation / legal meeting' — court recording is illegal
- Add Ukrainian (uk) and Polish (pl) as selectable audio transcription languages
- TRANSCRIBE_I18N translation object drives all status messages, labels, and trace text
- Apache ProxyTimeout raised to 1800s on server (was 300s — caused 504 on large files)
- set_time_limit(0) + ignore_user_abort(true) in api/transcribe.php
- applyTranscribeI18n() patches data-i18n / data-i18n-placeholder / data-i18n-aria attrs

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

assets/css/tools.css

@@ -1300,6 +1300,42 @@ p {
   margin-bottom: 0.35rem;
 }
 
+/* ─── UI Language switcher ────────────────────────────────────────────────── */
+
+.lang-switcher {
+  display: flex;
+  align-items: center;
+  gap: 0.375rem;
+  padding-bottom: 0.625rem;
+  margin-bottom: 0.25rem;
+  border-bottom: 1px solid var(--line);
+}
+
+.lang-btn {
+  background: var(--bg);
+  border: 1px solid var(--line);
+  border-radius: 9999px;
+  color: var(--muted);
+  cursor: pointer;
+  font-size: 0.7rem;
+  font-weight: 600;
+  letter-spacing: 0.03em;
+  padding: 0.2rem 0.55rem;
+  transition: background 0.15s, border-color 0.15s, color 0.15s;
+}
+
+.lang-btn:hover {
+  background: var(--soft-teal);
+  border-color: var(--teal);
+  color: var(--teal);
+}
+
+.lang-btn.is-active {
+  background: var(--teal);
+  border-color: var(--teal);
+  color: #fff;
+}
+
 .vocab-btn {
   font-size: 0.78rem;
   padding: 0.2rem 0.6rem;