Add editor reload wiring for baked toolpaths

[ajlennon]

Summary

• bake raster and waterline toolpaths to strategy-specific Curve3D resources at stable res:// paths
• add a Path3D placeholder and an editor-only reload hook that refreshes both the curve and AnimationPlayer when the selected strategy's .tres files change
• extend the headless bake proof to assert stable resource paths and scene wiring

Test plan

• Godot 4.6 headless import in the CI Docker image
• raster eartip bake (2555 Curve3D points; BAKE_OK)
• waterline eartip bake (7522 Curve3D points; WATERLINE_PROOF; BAKE_OK)
• In Godot editor, select EditorAssetReload, choose each Preview Strategy, rebake, and confirm ToolpathCurve plus AnimationPlayer refresh without reopening the scene

AI assistance

Implementation was assisted by Cursor. The human author remains responsible for review and submission.