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/op-helical.js

@@ -240,11 +240,10 @@ export class OpHelical extends CamOp {
     }
 
     async prepare(ops, progress) {
-        let { polyEmit, printPoint, setTool, setSpindle } = ops;
+        let { polyEmit, printPoint, setTool } = ops;
         let { tool, spindle, rate, feed } = this.op;
 
         setTool(tool, feed, rate);
-        setSpindle(spindle);
 
         let [ polys ] = this.sliceOut.map((s) => s.camLines);
         polys = polys.slice();
@@ -268,7 +267,7 @@ export class OpHelical extends CamOp {
             if (!closest) break;
             poly = polys[closestI]
             polys[closestI] = null;
-            printPoint = polyEmit(poly, 0, 1, poly.points[0])
+            printPoint = polyEmit(poly);
         }
     }
 }