重构: DRY截断正典改名收尾

- audit/utils.rs truncate_chars→truncate_chars_ellipsis 正典改名(补…语义),re-export 链同步
- record.rs/generate_image.rs/knowledge_inject.rs/tools/knowledge.rs 调用点全链更新
- df-ai context_helpers.rs 私有版跨 crate 不引依赖保留原名,加正典标注注释
- DRY #11 收口,同名不同义陷阱消除

src-tauri/src/commands/ai/generate_image.rs

@@ -49,7 +49,7 @@ use df_storage::db::Database;
 use df_storage::models::AiProviderRecord;
 use df_storage::secret::resolve_provider_secret;
 
-use crate::commands::ai::audit::truncate_chars;
+use crate::commands::ai::audit::truncate_chars_ellipsis;
 use crate::commands::ai::http::{
     build_client, execute_with_redirects, resolve_and_check_host, validate_url, MAX_REDIRECTS,
 };
@@ -184,7 +184,7 @@ pub(crate) async fn execute_generate_image(
     if !status.is_success() {
         // 错误响应读 body 摘要(截断 500 chars,截断时尾部补 …)帮助定位
         let err_text = resp.text().await.unwrap_or_default();
-        let snippet: String = truncate_chars(&err_text, 500);
+        let snippet: String = truncate_chars_ellipsis(&err_text, 500);
         anyhow::bail!(
             "图像生成端点返回 HTTP {}: {}",
             status.as_u16(),
@@ -459,7 +459,7 @@ async fn write_atomic(output_path: &str, data: &[u8]) -> anyhow::Result<()> {
 /// 走 audit truncate_chars 正典(截断时尾部补 …);错误文案无硬长度约束,允许多 1 字符。
 fn body_snippet(v: &Value) -> String {
     let s = v.to_string();
-    truncate_chars(&s, 500)
+    truncate_chars_ellipsis(&s, 500)
 }
 
 // ============================================================