Remove VisionBridge OCR (unused)

VisionBridge was a Swift library for Apple Vision OCR that was built
every compile but never actually used by any g3 tool.

Removed:
- vision-bridge/ Swift package directory
- src/ocr/ module (vision.rs, tesseract.rs, mod.rs)
- OCR methods from ComputerController trait
- OCR-related code from platform implementations
- TextLocation type (no longer needed)
- test_vision.rs example

Simplified:
- build.rs (now empty, no Swift compilation)
- MacOSController (no longer holds OCR engine)
- LinuxController and WindowsController (stub implementations)

Build time improvement: No more 'Building VisionBridge Swift package...'
messages on every compile.

crates/g3-computer-control/src/lib.rs

@@ -2,7 +2,6 @@
 #![allow(unexpected_cfgs)]
 
 pub mod macax;
-pub mod ocr;
 pub mod platform;
 pub mod types;
 pub mod webdriver;
@@ -30,16 +29,6 @@ pub trait ComputerController: Send + Sync {
         window_id: Option<&str>,
     ) -> Result<()>;
 
-    // OCR operations
-    async fn extract_text_from_screen(&self, region: Rect, window_id: &str) -> Result<String>;
-    async fn extract_text_from_image(&self, path: &str) -> Result<String>;
-    async fn extract_text_with_locations(&self, path: &str) -> Result<Vec<TextLocation>>;
-    async fn find_text_in_app(
-        &self,
-        app_name: &str,
-        search_text: &str,
-    ) -> Result<Option<TextLocation>>;
-
     // Mouse operations
     fn move_mouse(&self, x: i32, y: i32) -> Result<()>;
     fn click_at(&self, x: i32, y: i32, app_name: Option<&str>) -> Result<()>;