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-computer-control/examples/test_screenshot_fix.rs

@@ -4,17 +4,23 @@ use image::{ImageBuffer, RgbaImage};
 fn main() {
     let display = CGDisplay::main();
     let image = display.image().expect("Failed to capture screen");
-    
+
     let width = image.width() as u32;
     let height = image.height() as u32;
     let bytes_per_row = image.bytes_per_row() as usize;
     let data = image.data();
-    
+
     println!("Testing screenshot fix...");
-    println!("Image: {}x{}, bytes_per_row: {}", width, height, bytes_per_row);
+    println!(
+        "Image: {}x{}, bytes_per_row: {}",
+        width, height, bytes_per_row
+    );
     println!("Expected bytes per row: {}", width * 4);
-    println!("Padding per row: {} bytes", bytes_per_row - (width as usize * 4));
-    
+    println!(
+        "Padding per row: {} bytes",
+        bytes_per_row - (width as usize * 4)
+    );
+
     // OLD METHOD (broken) - treating data as continuous
     println!("\n=== OLD METHOD (BROKEN) ===");
     let mut old_rgba = Vec::with_capacity(data.len() as usize);
@@ -26,14 +32,14 @@ fn main() {
     }
     println!("Converted {} pixels", old_rgba.len() / 4);
     println!("Expected {} pixels", width * height);
-    
+
     // NEW METHOD (fixed) - handling row padding
     println!("\n=== NEW METHOD (FIXED) ===");
     let mut new_rgba = Vec::with_capacity((width * height * 4) as usize);
     for row in 0..height as usize {
         let row_start = row * bytes_per_row;
         let row_end = row_start + (width as usize * 4);
-        
+
         for chunk in data[row_start..row_end].chunks_exact(4) {
             new_rgba.push(chunk[2]); // R
             new_rgba.push(chunk[1]); // G
@@ -43,26 +49,34 @@ fn main() {
     }
     println!("Converted {} pixels", new_rgba.len() / 4);
     println!("Expected {} pixels", width * height);
-    
+
     // Save a small crop from both methods
     let crop_size = 200;
-    
+
     // Old method crop
-    let old_crop: Vec<u8> = old_rgba.iter().take((crop_size * crop_size * 4) as usize).copied().collect();
+    let old_crop: Vec<u8> = old_rgba
+        .iter()
+        .take((crop_size * crop_size * 4) as usize)
+        .copied()
+        .collect();
     if let Some(old_img) = ImageBuffer::from_raw(crop_size, crop_size, old_crop) {
         let old_img: RgbaImage = old_img;
         old_img.save("/tmp/screenshot_old_method.png").unwrap();
         println!("\nSaved OLD method crop to: /tmp/screenshot_old_method.png");
     }
-    
+
     // New method crop
-    let new_crop: Vec<u8> = new_rgba.iter().take((crop_size * crop_size * 4) as usize).copied().collect();
+    let new_crop: Vec<u8> = new_rgba
+        .iter()
+        .take((crop_size * crop_size * 4) as usize)
+        .copied()
+        .collect();
     if let Some(new_img) = ImageBuffer::from_raw(crop_size, crop_size, new_crop) {
         let new_img: RgbaImage = new_img;
         new_img.save("/tmp/screenshot_new_method.png").unwrap();
         println!("Saved NEW method crop to: /tmp/screenshot_new_method.png");
     }
-    
+
     println!("\nOpen both images to compare:");
     println!("  open /tmp/screenshot_old_method.png /tmp/screenshot_new_method.png");
 }