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/core/routes/api/admin_menu_config.py

@@ -30,6 +30,7 @@ from app.api.deps import (
 from app.modules.core.services.menu_service import MenuItemConfig, menu_service
 from app.modules.tenancy.services.platform_service import platform_service
 from app.modules.enums import FrontendType  # noqa: API-007 - Enum for type safety
+from app.utils.i18n import translate, DEFAULT_LANGUAGE
 from models.schema.auth import UserContext
 
 logger = logging.getLogger(__name__)
@@ -111,15 +112,39 @@ class MenuActionResponse(BaseModel):
 # =============================================================================
 
 
-def _build_menu_item_response(item: MenuItemConfig) -> MenuItemResponse:
-    """Convert MenuItemConfig to API response."""
+def _translate_label(label_key: str | None, language: str) -> str | None:
+    """
+    Translate a label key to the user's language.
+
+    Falls back to a readable version of the key if translation not found.
+    """
+    if not label_key:
+        return None
+
+    translated = translate(label_key, language=language)
+
+    # If translation returned the key itself, it wasn't found
+    # Create a readable fallback from the last part of the key
+    if translated == label_key:
+        parts = label_key.split(".")
+        last_part = parts[-1]
+        # Convert snake_case to Title Case
+        return last_part.replace("_", " ").title()
+
+    return translated
+
+
+def _build_menu_item_response(
+    item: MenuItemConfig, language: str = DEFAULT_LANGUAGE
+) -> MenuItemResponse:
+    """Convert MenuItemConfig to API response with translated labels."""
     return MenuItemResponse(
         id=item.id,
-        label=item.label,
+        label=_translate_label(item.label, language),
         icon=item.icon,
         url=item.url,
         section_id=item.section_id,
-        section_label=item.section_label,
+        section_label=_translate_label(item.section_label, language),
         is_visible=item.is_visible,
         is_mandatory=item.is_mandatory,
         is_super_admin_only=item.is_super_admin_only,
@@ -129,11 +154,12 @@ def _build_menu_item_response(item: MenuItemConfig) -> MenuItemResponse:
 def _build_menu_config_response(
     items: list[MenuItemConfig],
     frontend_type: FrontendType,
+    language: str = DEFAULT_LANGUAGE,
     platform_id: int | None = None,
     user_id: int | None = None,
 ) -> MenuConfigResponse:
-    """Build menu configuration response."""
-    item_responses = [_build_menu_item_response(item) for item in items]
+    """Build menu configuration response with translated labels."""
+    item_responses = [_build_menu_item_response(item, language) for item in items]
     visible_count = sum(1 for item in items if item.is_visible)
 
     return MenuConfigResponse(
@@ -177,7 +203,12 @@ async def get_platform_menu_config(
         f"for platform {platform.code} ({frontend_type.value})"
     )
 
-    return _build_menu_config_response(items, frontend_type, platform_id=platform_id)
+    # Use user's preferred language, falling back to default
+    language = current_user.preferred_language or DEFAULT_LANGUAGE
+
+    return _build_menu_config_response(
+        items, frontend_type, language=language, platform_id=platform_id
+    )
 
 
 @router.put("/platforms/{platform_id}")
@@ -300,8 +331,11 @@ async def get_user_menu_config(
         f"[MENU_CONFIG] Super admin {current_user.email} fetched their personal menu config"
     )
 
+    # Use user's preferred language, falling back to default
+    language = current_user.preferred_language or DEFAULT_LANGUAGE
+
     return _build_menu_config_response(
-        items, FrontendType.ADMIN, user_id=current_user.id
+        items, FrontendType.ADMIN, language=language, user_id=current_user.id
     )
 
 
@@ -448,14 +482,26 @@ async def get_rendered_admin_menu(
             is_super_admin=False,
         )
 
-    sections = [
-        MenuSectionResponse(
-            id=section["id"],
-            label=section.get("label"),
-            items=section["items"],
+    # Use user's preferred language, falling back to default
+    language = current_user.preferred_language or DEFAULT_LANGUAGE
+
+    # Translate section and item labels
+    sections = []
+    for section in menu.get("sections", []):
+        # Translate item labels
+        translated_items = []
+        for item in section.get("items", []):
+            translated_item = item.copy()
+            translated_item["label"] = _translate_label(item.get("label"), language)
+            translated_items.append(translated_item)
+
+        sections.append(
+            MenuSectionResponse(
+                id=section["id"],
+                label=_translate_label(section.get("label"), language),
+                items=translated_items,
+            )
         )
-        for section in menu.get("sections", [])
-    ]
 
     return RenderedMenuResponse(
         frontend_type=FrontendType.ADMIN.value,