fix: cross-platform compatibility for Windows support

- Use directories::BaseDirs for config path fallback instead of hardcoded Unix path
- Default to notepad on Windows instead of vi for editor commands
- Skip +N line argument for notepad in todo edit (notepad doesn't support it)

src/cli/commands/new.rs

@@ -24,7 +24,13 @@ pub fn run() -> Result<(), StreamdError> {
     drop(file);
 
     // Open in editor
-    let editor = std::env::var("EDITOR").unwrap_or_else(|_| "vi".to_string());
+    let editor = std::env::var("EDITOR").unwrap_or_else(|_| {
+        if cfg!(windows) {
+            "notepad".to_string()
+        } else {
+            "vi".to_string()
+        }
+    });
     let status = Command::new(&editor).arg(&preliminary_path).status()?;
 
     if !status.success() {