chore: add coverage.html to .gitignore

Prevent coverage report HTML files from being accidentally committed.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: jackspirou

.gitignore

@@ -17,9 +17,10 @@
 # Dependency directories (remove the comment below to include it)
 # vendor/
 
-# Coverage file
+# Coverage files
 coverage.txt
 coverage.out
+coverage.html
 
 # Go workspace file
 go.work