Feature: Move closest label to current selection point

### Your idea

It would be wonderful if there was a way (preferably with a keyboard shortcut) to move the closest label (in any label track) to the current selection point in the audio.

When an audio range is selected, it should move the nearest label to both ends. When only a point is selected, it should just move one label.

Having a setting that controls how close to the selection the label to be modified must be before changing it's position would be great too. Labels farther away than the set distance would not be modified.

### Problem to be solved

It's very difficult to move an existing label exactly to the point you want within the audio, and this would allow that to be done easily.

Adding a new label can be done pretty easily, but then you still need to clean up existing labels that aren't quite right.

### Prior art

_No response_

### Additional context

Work context: Splitting an audio file into segments

1. Select audio, use Analyze -> Label Sounds (or other feature like Analyze -> Regular Interval Labels) to place labels.
2. Adjust the selection point to a nearby better location (for instance: use key Z - Select Zero Crossing)
3. Use this new feature to adjust the nearest Label position to the current point, exactly where you want it

Start by tracing the existing Analyze → Label Sounds and Analyze → Regular Interval Labels entry points, along with the selection behavior used by Select Zero Crossing. Determine how label tracks, point selections, range selections, keyboard shortcuts, and a configurable distance limit are represented. Done means the nearest eligible label moves to the selected point or range ends without modifying labels beyond the configured distance.

Written by the indexing model from the issue text.