Dictionary entries and `'s`

**Describe the bug**
When a proper noun is added to the dictionary, it still flags the word as spelling error when 's is added to the word.

**To Reproduce**
Steps to reproduce the behavior:
1. Add word to dictionary
2. Find instance of word modified with "'s"
3. See error

**Expected behavior**
I assumed that a word added to the dictionary would be recognized even with the "'s"

**Platform**
I saw it occur in Obsidian - I did not yet get the cli to display correctly in iterm for me so I cannot yet confirm that.
I have the latest versions of MacOS, obsidian, and Harper (from `brew`)

**Additional context**
Looking forward to using Harper more!

Start by reproducing the issue with a proper noun added to the dictionary, then check how the dictionary handles the same word followed by "'s". Confirm the behavior in Harper's available interfaces, including Obsidian and the CLI if possible. Done means the dictionary entry is recognized with the possessive suffix without producing a spelling error.

Written by the indexing model from the issue text.