fix: remove unused import and method

src/modes/common.rs

@@ -60,19 +60,6 @@ pub enum ColumnType {
 }
 
 impl ColumnType {
-    /// Returns the human-readable string representation of the column type
-    pub fn as_str(&self) -> &str {
-        match self {
-            ColumnType::Id => "id",
-            ColumnType::Time => "time",
-            ColumnType::Size => "size",
-            ColumnType::Compression => "compression",
-            ColumnType::FileSize => "filesize",
-            ColumnType::FilePath => "filepath",
-            ColumnType::Tags => "tags",
-            ColumnType::Meta => "meta",
-        }
-    }
 
     /// Returns a Result with error message if the string is not a valid ColumnType
     pub fn from_str(s: &str) -> anyhow::Result<Self> {