feat: implement dynamic sidebar with server-side menu translation

- Add server-side translation for menu labels using user's preferred_language
- Replace hardcoded sidebar template with dynamic rendering from menu API
- Remove hardcoded section/page mappings in favor of menu discovery
- Fix locale file structure (move menu keys to top level to avoid double-nesting)
- Sidebar now fully driven by /admin/menu-config/render/admin API endpoint

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/tenancy/static/admin/js/platform-menu-config.js

@@ -52,9 +52,6 @@ function adminPlatformMenuConfig(platformCode) {
         },
 
         async init() {
-            // Load i18n translations
-            await I18n.loadModule('tenancy');
-
             // Guard against duplicate initialization
             if (window._platformMenuConfigInitialized) {
                 menuConfigLog.warn('Already initialized, skipping');
@@ -66,6 +63,8 @@ function adminPlatformMenuConfig(platformCode) {
             menuConfigLog.info('Platform code:', this.platformCode);
 
             try {
+                // Load tenancy translations for confirmations
+                await I18n.loadModule('tenancy');
                 await this.loadPlatform();
                 await this.loadPlatformMenuConfig();
                 menuConfigLog.info('=== PLATFORM MENU CONFIG PAGE INITIALIZED ===');