Remove vision tools (except take_screenshot) and macax tools

Vision tools removed:
- extract_text (OCR from image files)
- extract_text_with_boxes (OCR with bounding boxes)
- vision_find_text (find text in app windows)
- vision_click_text (find and click on text)
- vision_click_near_text (click near text labels)

macax tools removed:
- macax_list_apps
- macax_get_frontmost_app
- macax_activate_app
- macax_press_key
- macax_type_text

The LLM can now read images directly via read_image tool.
take_screenshot is retained for capturing application windows.

Files deleted:
- crates/g3-core/src/tools/vision.rs
- crates/g3-core/src/tools/macax.rs
- docs/macax-tools.md

Updated tool counts: 12 core + 15 webdriver = 27 total

crates/g3-core/src/tools/executor.rs

@@ -20,7 +20,6 @@ pub struct ToolContext<'a, W: UiWriter> {
     pub computer_controller: Option<&'a Box<dyn g3_computer_control::ComputerController>>,
     pub webdriver_session: &'a Arc<RwLock<Option<Arc<tokio::sync::Mutex<WebDriverSession>>>>>,
     pub webdriver_process: &'a Arc<RwLock<Option<tokio::process::Child>>>,
-    pub macax_controller: &'a Arc<RwLock<Option<g3_computer_control::MacAxController>>>,
     pub background_process_manager: &'a Arc<BackgroundProcessManager>,
     pub todo_content: &'a Arc<RwLock<String>>,
     pub pending_images: &'a mut Vec<g3_providers::ImageContent>,