⚡ Bolt: [performance improvement]

[coredipper]

💡 What: Replaced several instances of O(N²) list deduplication (using if item not in seen_list: seen_list.append(item)) with O(N) hash-based deduplication (list(dict.fromkeys(...))).
🎯 Why: Because checking membership in a Python list is an O(N) operation, doing it inside a loop over N items creates an O(N²) algorithmic bottleneck. Using dictionaries (which preserve insertion order in Python 3.7+) reduces this to O(N).
📊 Impact: Expected performance improvement in loops processing collections of sources and markers while producing functionally identical ordered output.
🔬 Measurement: Run the test suite (cd scrip && uv run pytest tests/ and cd harness && uv run pytest tests/) to verify correct order preservation and deduplication.

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PR created automatically by Jules for task 16295306975210764240 started by @coredipper

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