Improve UI preferences and data export

[bobthecomputer]

Summary

• allow muting the daily toast and persist preference in SQLite
• add dark theme configuration and mobile-friendly layout
• export progress to CSV and reset history from the Progress tab
• include Lucky Drop notice in the toast
• update tests for progress utilities and digest helpers
• add player watch alerts and optional Qwen-based coaching

Testing

• python -m py_compile clash_api.py analysis.py streamlit_app.py youtube_api.py coach.py meta.py deck_optimizer.py goals.py gc_coach.py merge_stats.py digest.py auth.py player_watch.py tests/*.py
• pip install -r requirements.txt
• python -m unittest discover tests -v

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https://chatgpt.com/codex/tasks/task_e_6877d966006083228cf7cde54f49cc7f