Position of the QED symbol at the end of a proof environment might be altered

### Issue

When the last paragraph inside a `proof` environment is altered by `lua-widow-control`, the QED symbol seems to be also moved as part of the text, resulting in that it might no longer stay at the rightmost of the line.

Here is an example when `lua-widow-control` is not used:

And this is when `lua-widow-control` is used:

Since the spacing between the last word and the QED symbol appears the same, I suspect that `lua-widow-control` is altering this paragraph as if QED symbol is part of the text.

(But sorry, I was not able to reproduce this behavior with a MWE, and the log file of my current document is longer than 65536 characters so I cannot paste it under the text box below...)

### Expected Behavior

I expect that `lua-widow-control` would only alter the text of the last paragraph of inside a `proof` environment, and somehow leave the QED symbol untouched and only add it later, when the text is already altered. The QED symbol might then always stay at the rightmost of the line, as it should be.

### Reproduction

```TeX

```

### Log File

```plain text

```

### Format

LaTeX

### Distribution

TeX Live

### Distribution Version

TeX Live 2025

### Lua-widow-control Version

3.0.1, tried with both the CTAN and the current GitHub versions

### Other Relevant Packages and Versions

_No response_

### Other

_No response_