chore: checkpoint ai search comments and i18n foundation

backend/src/models/_entities/site_settings.rs

@@ -28,6 +28,18 @@ pub struct Model {
     pub location: Option<String>,
     #[sea_orm(column_type = "JsonBinary", nullable)]
     pub tech_stack: Option<Json>,
+    pub ai_enabled: Option<bool>,
+    pub ai_provider: Option<String>,
+    pub ai_api_base: Option<String>,
+    #[sea_orm(column_type = "Text", nullable)]
+    pub ai_api_key: Option<String>,
+    pub ai_chat_model: Option<String>,
+    pub ai_embedding_model: Option<String>,
+    #[sea_orm(column_type = "Text", nullable)]
+    pub ai_system_prompt: Option<String>,
+    pub ai_top_k: Option<i32>,
+    pub ai_chunk_size: Option<i32>,
+    pub ai_last_indexed_at: Option<DateTimeWithTimeZone>,
 }
 
 #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]