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/settings/settings.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"gitea.dooplex.hu/admin/felhom-controller/internal/appbackup"
+	"gitea.dooplex.hu/admin/felhom-controller/internal/i18n"
 )
 
 // Settings holds customer-modifiable overrides and cached state.
@@ -34,6 +35,9 @@ type Settings struct {
 	// OPTIONAL bcrypt hash for a per-share password, ALWAYS SEPARATE from the admin PasswordHash above.
 	// The token is a secret and must never be logged.
 	LauncherShareToken        string `json:"launcher_share_token,omitempty"`
+	// Language (v0.247.0, i18n) — the household's dashboard language: "hu" | "en". Empty means never
+	// chosen and reads as Hungarian (GetLanguage). Reported to the hub so its e-mails can follow.
+	Language string `json:"language,omitempty"`
 	LauncherSharePasswordHash string `json:"launcher_share_password_hash,omitempty"`
 
 	// FileBrowser admin login (R-513, v0.243.0). Every box used to accept admin/admin. The controller
@@ -809,6 +813,26 @@ func (s *Settings) SetBackupWindowStart(start string) error {
 	return s.save()
 }
 
+// GetLanguage returns the household's dashboard language, normalised: anything unset or unknown is
+// Hungarian (i18n.Default).
+func (s *Settings) GetLanguage() string {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return i18n.Normalize(s.Language)
+}
+
+// SetLanguage stores the household's dashboard language and saves. Only a supported language is
+// accepted; anything else is refused and nothing is written.
+func (s *Settings) SetLanguage(lang string) error {
+	if !i18n.IsSupported(lang) {
+		return fmt.Errorf("unsupported language %q", lang)
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.Language = lang
+	return s.save()
+}
+
 // GetLauncherShareToken returns the guest-launcher capability token ("" = sharing disabled).
 func (s *Settings) GetLauncherShareToken() string {
 	s.mu.RLock()