Add tutorial/state.json to .gitignore

State file tracks individual tutorial progress and should not be committed.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: garwin00

.gitignore

@@ -5,6 +5,7 @@ node_modules/
 # Generated by hooks at runtime
 tutorial/current-lesson.md
 tutorial/validation-result.txt
+tutorial/state.json
 
 # Exercise artifacts (created by students during lessons)
 exercises/sample-app/SPEC.md