Strings containing only punctuation or symbols used as glossary terms are not highlighted in the source field if they are at the beginning of a source word

### Describe the issue

Some strings containing only (perhaps consecutive?) punctuation or symbols used as glossary terms are not highlighted in the source field if they are at the beginning of a source word, but are highlighted at the end of a source word.

I am not sure if this is really necessary. But some users do add glossary terms that contain only punctuation or symbols.

### I already tried

- [x] I've read and searched [the documentation](https://docs.weblate.org/).
- [x] I've searched for similar filed issues in this repository.

### Steps to reproduce the behavior

1. Add glossary terms that contain only punctuation or symbols.
2. Find a string that matches the glossary term above and open it in the editor.

### Expected behavior

Highlight the (perhaps consecutive?) punctuation or symbols used as glossary terms in the source field if they are at the beginning of a source word.

### Screenshots

Example: https://hosted.weblate.org/translate/godot-engine/godot-docs/zh_Hans/?checksum=8325137afeb8593a

### Exception traceback

```pytb

```

### How do you run Weblate?

weblate.org service

### Weblate versions

Weblate 5.10.3-dev

### Weblate deploy checks

```shell

```

### Additional context

Related to #3023, but only specific to punctuation and symbols. It may be easier to implement.