Use canonical path and DataModel::from_markdown

Resolve the input path with std::fs::canonicalize and pass the canonical Path to DataModel::from_markdown instead of reading the file into a string and calling from_markdown_string. This normalizes the path and delegates file parsing to DataModel, avoiding an extra read_to_string here.

Author: JR-1991

src/markdown/frontmatter.rs

@@ -186,8 +186,8 @@ impl ImportType {
         } else {
             path.to_string()
         };
-        let data = std::fs::read_to_string(path)?;
-        let model = DataModel::from_markdown_string(&data)?;
+        let path = std::fs::canonicalize(path)?;
+        let model = DataModel::from_markdown(&path)?;
         Ok(model)
     }
 }