feat: clickable zoom reset, Pan tool (H), and batch command support

- Clicking the zoom percentage in the menu bar resets zoom to 100%
- New Pan tool (H key) for explicit left-click-drag panning mode
- Batch command support: agents can send multiple operations in a
  single WebSocket message via {"type": "Batch", "requests": [...]}
  with sequential execution and collected results
- New MCP tool 'batch' accepts a JSON array of request objects
- Nested batches rejected with clear error message
- Updated AGENTS.md with .app rebuild requirement

AGENTS.md

@@ -30,8 +30,12 @@ cargo test -- --nocapture      # Show println! output
 
 cargo check                    # Type check only (fast)
 cargo doc --open               # Generate and open docs
+
+./scripts/bundle-macos.sh --install  # Rebuild + install .app to /Applications
 ```
 
+**IMPORTANT:** After every release build or code change that requires testing the running app, you MUST run `./scripts/bundle-macos.sh --install` to update the macOS `.app` bundle in `/Applications`. The running `Augmented Canvas.app` uses a copied binary — a bare `cargo build --release` alone does NOT update it. Kill the running app first with `pkill -f "Augmented Canvas"`, then rebuild and relaunch with `open "/Applications/Augmented Canvas.app"`.
+
 ## Project Structure
 
 ```