fix: clean up test fixtures and remove stale .bak test files

- Reset gitea settings after bug tests to prevent cross-test contamination
- Add deleted_at and deleted_by fields to ingress proxy test instance creation
- Call refresh_snapshot after ingress proxy test setup and teardown
- Remove orphaned .bak test files (test_attachments.py.bak, test_demo.py.bak) that were left behind from a previous refactor

tests/api/bugs/create.py

@@ -144,6 +144,8 @@ def gitea_env():
     set_setting("bug_ai_enhance", "0")
     yield fake
     runtime.set_client(None)
+    for key in ("gitea_base_url", "gitea_owner", "gitea_repo", "gitea_token"):
+        set_setting(key, "")
     for table in ("bug_tickets", "bug_comment_authors"):
         for row in list(get_table(table).find()):
             get_table(table).delete(uid=row["uid"])