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/run/minion.js

@@ -12,7 +12,7 @@ import { doTopShells } from '../mode/fdm/post.js';
 import { newPoint } from '../../geo/point.js';
 import { polygons as POLY } from '../../geo/polygons.js';
 import { sliceZ, sliceConnect } from '../../geo/slicer.js';
-import { Slicer as cam_slicer } from '../mode/cam/slicer.js';
+import { Slicer as cam_slicer } from '../mode/cam/slicer_cam.js';
 import { Slicer as topo_slicer } from '../mode/cam/slicer_topo.js';
 import { Probe, Trace, raster_slice } from '../mode/cam/topo3.js';
 import { Topo as Topo4, rotatePoints } from '../mode/cam/topo4.js';