fix: add shell_environment module to web_main.rs

Fixes Windows build by ensuring shell_environment is available
for both main.rs and web_main.rs binaries.

Author: jms830

src-tauri/src/web_main.rs

@@ -4,6 +4,7 @@ mod checkpoint;
 mod claude_binary;
 mod commands;
 mod process;
+mod shell_environment;
 mod web_server;
 
 #[derive(Parser)]