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/tools/knowledge.rs

@@ -30,7 +30,7 @@ use df_storage::db::Database;
 use df_storage::models::KnowledgeRecord;
 use df_types::types::new_id;
 
-use crate::commands::ai::audit::truncate_chars;
+use crate::commands::ai::audit::truncate_chars_ellipsis;
 use crate::commands::ai::knowledge_inject::{extract_query_keywords, spawn_embedding_for_record};
 use crate::commands::knowledge_timeline::KnowledgeTimeline;
 use crate::commands::now_millis;
@@ -81,7 +81,7 @@ pub fn register(registry: &mut AiToolRegistry, db: &Arc<Database>) {
                     serde_json::json!({
                         "title": k.title,
                         "kind": k.kind,
-                        "content": truncate_chars(&k.content, SEARCH_CONTENT_SNIPPET_LEN),
+                        "content": truncate_chars_ellipsis(&k.content, SEARCH_CONTENT_SNIPPET_LEN),
                         "status": k.status,
                         "reuse_count": k.reuse_count,
                     })