CAM routing refactor, area operation, and taper ball tool implementation

Major routing improvements:
- Refactor depth-first routing algorithm for better path optimization
- Reimplemented outline, roughing, pocket, and trace as area operation wrappers
- Add pocket shadow travel routing with optimized descent using travel bounds
- Improve contour routing with arc detection and polyEmit arc strategy
- Add area smoothing and ease-down options
- Fix outline handling with thru holes and surface reversal on tip2tip
- Move widget shadow methods into widget class for faster hole detection
- Better camInnerFirst support and proper feed/plunge defaults

Tool system improvements:
- Implement taper ball tool type with full support
- Add renderTool2() for profile-based visualization
- Convert tool menu to init code with bound vars
- Fix auto tool and auto spindle for prep operations
- Update tool profile generation for taperball geometry
- Add calcTaperBallExtent() for proper ball tangency calculations

Code cleanup:
- Remove duplicated slicer code from specialized slicers
- Asyncify shadowAt operations
- Deprecate pocket engrave operation
- Simplify upNover implementation
- Fix animation with new tool+settings requirements

src/kiri/mode/cam/export.js

@@ -256,6 +256,11 @@ export function cam_export(print, online) {
             return;
         }
 
+        // skip arc points for display only
+        if (out.emit === -1) {
+            return;
+        }
+
         let dx = opt.dx || newpos.x - pos.x,
             dy = opt.dy || newpos.y - pos.y,
             dz = opt.dz || newpos.z - pos.z,