Reset all optimization results (sweep DB + winner files) with a confirmation gate.

## When to use

Run `/reset` before any change that invalidates historical results:
- Scoring formula change (`config.py:composite_score()`)
- Trailing stop simulation change
- Data export column change (new signals, renamed columns)

**First check `/planChange`** if you haven't already — it will tell you whether the pending change actually requires a reset and suggest batching with other pending DB-invalidating changes.

## Steps

1. Show the current DB row counts so the user knows what will be lost:
   ```
   python3 mine_sweep_db.py 2>/dev/null | head -40
   ```
   Summarize: total rows, combos with data, and approximate optimization hours represented.

2. Run the dry-run to show exactly what files will be deleted:
   ```
   python3 tools/reset_results.py
   ```

3. Ask the user to confirm:
   > ⚠️ **This will permanently delete the above files.** The sweep DB and all winner files will be gone. Optimization runs will need to start from scratch.
   >
   > Are you sure you want to proceed? (yes / no)

4. Only if the user explicitly confirms — apply the reset:
   ```
   python3 tools/reset_results.py --apply
   ```

5. Confirm what was deleted, then remind:
   > Reset complete. Next steps:
   > - Implement your change (if not done already)
   > - Run a short validation: `python3 run_btc.py --hours 0.5 --tfs 4H` to confirm the new simulation produces sensible results before committing to a long run
   > - Then kick off a full optimization run