RichText widget put extraneous space before last exclamation point in Markdown content

[jancona]

Checklist

• I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

My code is populating a RichText widget with Markdown text. When the content contains exclamation points, it displays an extra space before the last exclamation point.

How to reproduce

See the example code and output below.

Screenshots

No response

Example code

This code snippet:

	fmt.Println("widget.NewRichTextWithText:")
	rt := widget.NewRichTextWithText("First! Hi!")
	for i, s := range rt.Segments {
		fmt.Printf("rt.Segments[%d]: %#v\n", i, s)
	}
	fmt.Println("widget.NewRichTextFromMarkdown:")
	rt = widget.NewRichTextFromMarkdown("First! Hi!")
	for i, s := range rt.Segments {
		fmt.Printf("rt.Segments[%d]: %#v\n", i, s)
	}

produces this output:

widget.NewRichTextWithText:
rt.Segments[0]: &widget.TextSegment{Style:widget.RichTextStyle{Alignment:0, ColorName:"foreground", Inline:true, SizeName:"text", TextStyle:fyne.TextStyle{Bold:false, Italic:false, Monospace:false, Symbol:false, TabWidth:0, Underline:false}, concealed:false}, Text:"First! Hi!", parent:(*widget.RichText)(nil)}
widget.NewRichTextFromMarkdown:
rt.Segments[0]: &widget.TextSegment{Style:widget.RichTextStyle{Alignment:0, ColorName:"foreground", Inline:true, SizeName:"text", TextStyle:fyne.TextStyle{Bold:false, Italic:false, Monospace:false, Symbol:false, TabWidth:0, Underline:false}, concealed:false}, Text:"First! Hi ", parent:(*widget.RichText)(nil)}
rt.Segments[1]: &widget.TextSegment{Style:widget.RichTextStyle{Alignment:0, ColorName:"foreground", Inline:true, SizeName:"text", TextStyle:fyne.TextStyle{Bold:false, Italic:false, Monospace:false, Symbol:false, TabWidth:0, Underline:false}, concealed:false}, Text:"!", parent:(*widget.RichText)(nil)}
rt.Segments[2]: &widget.TextSegment{Style:widget.RichTextStyle{Alignment:0, ColorName:"foreground", Inline:false, SizeName:"text", TextStyle:fyne.TextStyle{Bold:false, Italic:false, Monospace:false, Symbol:false, TabWidth:0, Underline:false}, concealed:false}, Text:"", parent:(*widget.RichText)(nil)}

The first TextSegment in the Markdown case has an extra space after Hi that wasn't in the input text. The space is also shown in the rendered widget.

Fyne version

2.5.4

Go compiler version

go1.23.4 darwin/arm64

Operating system and version

MacOS Sequoia 15.3

Additional Information

A user has also reported the issue on Linux.

I'm new to Fyne, so it's possible that I'm doing something wrong.

My code is based on Fybro and the code in question is unchanged. See here https://github.com/andydotxyz/fybro/blob/main/ui_message.go#L113