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/src/ocr/mod.rs

@@ -7,7 +7,7 @@ use async_trait::async_trait;
 pub trait OCREngine: Send + Sync {
     /// Extract text with locations from an image file
     async fn extract_text_with_locations(&self, path: &str) -> Result<Vec<TextLocation>>;
-    
+
     /// Get the name of the OCR engine
     fn name(&self) -> &str;
 }