[add] i18n support zh,en

api/app/i18n/README.md

@@ -0,0 +1,61 @@
+# Internationalization (i18n) Module
+
+This module provides internationalization support for the MemoryBear API.
+
+## Components
+
+- `service.py` - Translation service and core translation logic
+- `middleware.py` - Language detection middleware
+- `dependencies.py` - FastAPI dependency injection functions
+- `exceptions.py` - Internationalized exception classes
+
+## Usage
+
+### Basic Translation
+
+```python
+from app.i18n import t
+
+# Simple translation
+message = t("common.success.created")
+
+# Parameterized translation
+message = t("common.validation.required", field="Name")
+```
+
+### Enum Translation
+
+```python
+from app.i18n import t_enum
+
+# Translate enum value
+role_display = t_enum("workspace_role", "manager")
+```
+
+### In FastAPI Endpoints
+
+```python
+from fastapi import Depends
+from app.i18n.dependencies import get_translator
+
+@router.post("/workspaces")
+async def create_workspace(
+    data: WorkspaceCreate,
+    t: Callable = Depends(get_translator)
+):
+    workspace = await workspace_service.create(data)
+    return {
+        "success": True,
+        "message": t("workspace.created_successfully"),
+        "data": workspace
+    }
+```
+
+## Configuration
+
+See `app/core/config.py` for i18n configuration options:
+
+- `I18N_DEFAULT_LANGUAGE` - Default language (default: "zh")
+- `I18N_SUPPORTED_LANGUAGES` - Supported languages (default: "zh,en")
+- `I18N_ENABLE_TRANSLATION_CACHE` - Enable caching (default: true)
+- `I18N_LOG_MISSING_TRANSLATIONS` - Log missing translations (default: true)