feat(stage5): Rust read_file_base64 导出辅助命令

src-tauri/src/commands.rs

@@ -371,3 +371,26 @@ pub fn db_recovery_delete(db: State<'_, AppDb>, doc_key: String) -> Result<(), S
     let conn = lock_db(&db)?;
     storage::recovery_delete(&conn, &doc_key)
 }
+
+// ————————————————— 阶段 5：导出辅助 —————————————————
+
+fn base64_encode(data: &[u8]) -> String {
+    const TABLE: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+    let mut out = String::with_capacity((data.len() + 2) / 3 * 4);
+    for chunk in data.chunks(3) {
+        let b = [chunk[0], *chunk.get(1).unwrap_or(&0), *chunk.get(2).unwrap_or(&0)];
+        let n = ((b[0] as u32) << 16) | ((b[1] as u32) << 8) | b[2] as u32;
+        out.push(TABLE[(n >> 18) as usize & 63] as char);
+        out.push(TABLE[(n >> 12) as usize & 63] as char);
+        out.push(if chunk.len() > 1 { TABLE[(n >> 6) as usize & 63] as char } else { '=' });
+        out.push(if chunk.len() > 2 { TABLE[n as usize & 63] as char } else { '=' });
+    }
+    out
+}
+
+/// 读任意文件并以 base64 返回（导出图片内嵌、DOCX 导入共用）。
+#[tauri::command]
+pub fn read_file_base64(path: String) -> Result<String, String> {
+    let bytes = fs::read(&path).map_err(|e| format!("读取文件失败：{e}"))?;
+    Ok(base64_encode(&bytes))
+}

src-tauri/src/lib.rs

@@ -42,6 +42,7 @@ pub fn run() {
             commands::db_recovery_list,
             commands::db_recovery_save,
             commands::db_recovery_delete,
+            commands::read_file_base64,
         ])
         .run(tauri::generate_context!())
         .expect("error while running new-markdown");