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-planner/tests/logging_test.rs

@@ -7,38 +7,40 @@ use std::path::Path;
 fn test_log_files_created() {
     // This test verifies that the logging functions work correctly
     // by checking that files can be created in the logs directory
-    
+
     // Clean up any existing test logs
     let _ = fs::remove_dir_all("logs");
-    
+
     // Create logs directory
     fs::create_dir_all("logs").expect("Failed to create logs directory");
-    
+
     // Verify directory exists
     assert!(Path::new("logs").exists());
     assert!(Path::new("logs").is_dir());
-    
+
     // Test writing a code report
     let test_report = "Test codebase report\nLine 2\nLine 3";
     let timestamp = chrono::Local::now().format("%Y%m%d_%H%M%S").to_string();
     let report_filename = format!("logs/code_report_{}.log", timestamp);
-    
+
     fs::write(&report_filename, test_report).expect("Failed to write code report");
     assert!(Path::new(&report_filename).exists());
-    
+
     let content = fs::read_to_string(&report_filename).expect("Failed to read code report");
     assert_eq!(content, test_report);
-    
+
     // Test writing discovery commands
     let commands_filename = format!("logs/discovery_commands_{}.log", timestamp);
-    let test_commands = "# Discovery Commands\n# Generated by g3-planner\n\nls -la\ncat README.md\n";
-    
+    let test_commands =
+        "# Discovery Commands\n# Generated by g3-planner\n\nls -la\ncat README.md\n";
+
     fs::write(&commands_filename, test_commands).expect("Failed to write discovery commands");
     assert!(Path::new(&commands_filename).exists());
-    
-    let content = fs::read_to_string(&commands_filename).expect("Failed to read discovery commands");
+
+    let content =
+        fs::read_to_string(&commands_filename).expect("Failed to read discovery commands");
     assert_eq!(content, test_commands);
-    
+
     // Clean up
     let _ = fs::remove_file(&report_filename);
     let _ = fs::remove_file(&commands_filename);
@@ -48,11 +50,11 @@ fn test_log_files_created() {
 fn test_filename_format() {
     // Verify the filename format matches the tool_calls log format
     let timestamp = chrono::Local::now().format("%Y%m%d_%H%M%S").to_string();
-    
+
     // Check format: YYYYMMDD_HHMMSS
     assert_eq!(timestamp.len(), 15); // 8 digits + underscore + 6 digits
     assert!(timestamp.contains('_'));
-    
+
     let parts: Vec<&str> = timestamp.split('_').collect();
     assert_eq!(parts.len(), 2);
     assert_eq!(parts[0].len(), 8); // YYYYMMDD