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

docs/architecture.md

@@ -191,7 +191,6 @@ Key modules:
 - `platform/` - Platform-specific implementations (macOS, Linux, Windows)
 - `webdriver/` - Safari and Chrome WebDriver integration
 - `ocr/` - Text extraction (Tesseract, Apple Vision)
-- `macax/` - macOS Accessibility API controller
 
 **Platform support**:
 - **macOS**: Core Graphics, Cocoa, screencapture, Vision framework