Slate v2 select should turn Point into a collapsed selection

What happened

The docs already described Transforms.select(...) in terms of Location, but the current helper only handled Range | null.

The next honest cut was not full legacy parity. It was just this:

• accept a Path
• accept a Point
• turn a Path into the exact current node range
• turn a Point into a collapsed selection

What fixed it

The helper now accepts:

• Path
• Range
• Point
• null

When the target is:

• a Path, it creates the exact current node range
• a Point, it creates a collapsed selection at that point

Reusable rule

For Slate v2 selection helpers:

• widen Location support in honest cuts
• if a smaller location can be represented exactly as a range, do that first
• do not claim broad path/location parity before the engine actually owns it

If select(...) can already express a smaller case exactly, that is the right next cut. Not a bigger lie.