v0.247.0: i18n spike — the dashboard can speak English, Hungarian byte-identical

Message bundles (internal/i18n) expanded into templates before parsing, one
template set per language. Launcher, /backups, /apps/<slug> and the layout
converted; household language setting, POST /settings/language, ?lang= override,
report field. Parity test against fixtures captured from unconverted templates;
copy gates read templates expanded; new i18n_missing_gate.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/templates/backups_shared.html

@@ -10,9 +10,8 @@
 {{define "backups_empty"}}
 <div class="backup-empty-state">
     <div class="backup-empty-icon">&#128737;</div>
-    <h3>Biztonsági mentés nincs beállítva</h3>
-    <p>A biztonsági mentés funkció nem aktív.<br>
-    Kérjük, vegye fel a kapcsolatot a Felhom csapattal a beállításhoz.</p>
+    <h3>{{T "backups_shared.empty_title"}}</h3>
+    <p>{{T "backups_shared.empty_body"}}</p>
 </div>
 {{end}}