Pen tool clicking an anchor to turn it sharp shouldn't rely on snapping

[Keavon]

In the Pen tool, clicking to turn a point sharp relies on snapping being enabled to work, which is bad:

https://github.com/user-attachments/assets/70c74839-2519-42a5-8d40-af4a459da912

It should be able to do that irrespective of the snapping system. Essentially, the tool should have its own self-contained implementation of snapping just for the actively being-drawn-from segment endpoint, which is always active even when the snapping system is disabled, and the real snapping system shouldn't interfere with it.