🧪 Add missing fallback test for json.loads TypeError in load_shown

[google-labs-jules]

🎯 What: The load_shown function in hooks/utils.py catches TypeError when reading the state file (which can occur if json.load(f) returns a non-iterable like int which we try to wrap in set()). However, there wasn't a dedicated test ensuring this exact fallback path was executed completely.
📊 Coverage: A new test test_load_shown_handles_typeerror is added in tests/test_utils.py which mocks json.load to specifically raise TypeError. This guarantees the TypeError exception path in load_shown is covered and won't crash the script.
✨ Result: Test coverage and resilience have improved for the JSON deserialization error path. The code is safer to refactor because all branches are explicitly verified.

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PR created automatically by Jules for task 3931970502000165896 started by @zknpr

[google-labs-jules]

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