refactor(winreg): reorganize Windows registry utilities into extra module

Move winreg_extra functionality into new extra/winreg module and restructure project layout
Add Windows icon handling utilities in extra/windows module
Update dependencies and clean up unused wincmd module

wfassoc_exec/src/main.rs

@@ -117,6 +117,7 @@ fn run_unregister(cli: &Cli, target: &Target) -> Result<()> {
 fn run_query(cli: &Cli) -> Result<()> {
     let composition = Composition::new(cli)?;
 
+    // Show file association
     let mut table = Table::new();
     table.set_header(["Extension", "Hybrid", "User", "System"]);