Fix: test runner UX bugs and improve Butler test isolation

[kamilansri]

Summary

This PR addresses several usability and robustness issues in the manual test runner (run_tests.py) and improves the isolation of the Butler repository creation tests to prevent environment side effects.

Changes

run_tests.py (Test Runner)

• Fixed "Continue" Logic: The script no longer prompts the user to "Continue with remaining tests?" after the final test has already completed.
• Robust Argument Parsing: Added validation for test range arguments. Inputs like 1-, 1-3-5, or non-numeric strings now return friendly error messages instead of crashing with a traceback.
• Graceful Exit: Added KeyboardInterrupt handling to ensure a clean exit (without tracebacks) when the user presses Ctrl+C.

Butler Creation Test Script

• Removed Hardcoded Paths: Replaced unsafe hardcoded paths (e.g., /tmp/test_repo) with tempfile.TemporaryDirectory() context managers. This ensures tests run in complete isolation and cleans up artifacts automatically, preventing permission errors or stale data from previous runs.
• Dependency Safety: Added try/except blocks around ripple and lsst imports to allow the script to fail gracefully or skip specific checks if the environment is not fully configured.
• Method Safety: Added checks to ensure private methods (like _detect_instrument) exist before attempting to test them, preventing crashes during refactors.

Testing

1. Run python run_tests.py 1-4 and verify the runner does not ask to continue after the last test.
2. Run python run_tests.py invalid-input to verify the script handles errors without crashing.
3. Run the Butler test script multiple times in quick succession to ensure no temporary file collisions occur.