feat(pages): add multi-language support for landing pages

Implement internationalization system for landing pages:
- Database model for storing language-specific translations
- Language configuration with default and enabled languages
- Language switcher in navigation across all templates
- Translation management UI in settings
- Support for 15 languages including English, Spanish, German, French, Japanese, Chinese
- Auto-detection and manual language selection
- AI-powered translation generation capability

modules/pages/config.go

@@ -67,6 +67,9 @@ type LandingConfig struct {
 
 	// A/B testing experiments
 	Experiments ExperimentConfig `yaml:"experiments,omitempty"`
+
+	// Multi-language support
+	I18n I18nConfig `yaml:"i18n,omitempty"`
 }
 
 // BrandConfig represents brand/identity settings
@@ -233,6 +236,33 @@ type ExperimentConfig struct {
 	ApprovalRequired bool `yaml:"approval_required,omitempty"`
 }
 
+// I18nConfig represents multi-language settings for the landing page
+type I18nConfig struct {
+	DefaultLang string   `yaml:"default_lang,omitempty" json:"default_lang,omitempty"`
+	Languages   []string `yaml:"languages,omitempty" json:"languages,omitempty"`
+}
+
+// LanguageDisplayNames returns a map of language codes to display names
+func LanguageDisplayNames() map[string]string {
+	return map[string]string{
+		"en": "English",
+		"es": "Espanol",
+		"de": "Deutsch",
+		"fr": "Francais",
+		"ja": "Japanese",
+		"zh": "Chinese",
+		"pt": "Portugues",
+		"ru": "Russian",
+		"ko": "Korean",
+		"it": "Italiano",
+		"hi": "Hindi",
+		"ar": "Arabic",
+		"nl": "Nederlands",
+		"pl": "Polski",
+		"tr": "Turkish",
+	}
+}
+
 // AdvancedConfig represents advanced settings
 type AdvancedConfig struct {
 	CustomCSS      string            `yaml:"custom_css,omitempty"`