add context window monitor

Writes the current context window to logs/current_context_window (uses a symlink to a session ID).

This PR was unfortunately generated by a different LLM and did a ton of superficial reformating, it's actually a fairly small and benign change, but I don't want to roll back everything. Hope that's ok.

crates/g3-console/examples/test_api.rs

@@ -3,13 +3,15 @@ use g3_console::process::ProcessDetector;
 
 fn main() {
     let mut detector = ProcessDetector::new();
-    
+
     match detector.detect_instances() {
         Ok(instances) => {
             println!("Found {} instances:", instances.len());
             for instance in instances {
-                println!("  - PID: {}, Workspace: {:?}, Type: {:?}", 
-                    instance.pid, instance.workspace, instance.instance_type);
+                println!(
+                    "  - PID: {}, Workspace: {:?}, Type: {:?}",
+                    instance.pid, instance.workspace, instance.instance_type
+                );
             }
         }
         Err(e) => {