"OS" flagged even though it's in `dictionary.dict`

Right here around line 7568:
```
OR/CNO # Oregon
OS/ONgJ
OSHA/Og # agency
```
Not sure it should be marked as a proper noun or adjective though. I'll check and probably adjust those in my upcoming dictionary curation PR.

Start in dictionary.dict around line 7568 and inspect the OS entry alongside the neighboring entries. Confirm whether its proper-noun or adjective classification is intended, then verify that the grammar checker no longer flags OS incorrectly; the issue notes that this may be handled in an upcoming dictionary curation PR.

Written by the indexing model from the issue text.