link browser user dictionary to file system user dictionary

**What problem does this solve?**
Having to maintain differing user dictionaries.

**Proposed Solution**
writing and reading to https://writewithharper.com/docs/integrations/language-server#User-Dictionary

**Examples**

**Component**
- [ ] Core engine
- [x] Plugin/Extension
- [ ] Other: _____

**Additional Context**
Awesome project! Keep up the good work!

Start with the linked User-Dictionary documentation and inspect the plugin/extension entry point that handles browser dictionaries. Determine how the file-system dictionary should be read and written, then verify that both dictionaries stay linked without requiring separate maintenance.

Written by the indexing model from the issue text.