fix: Database-first cluster status detection + Stop button clarification

CRITICAL FIX (Nov 30, 2025):
- Dashboard showed 'idle' despite 22+ worker processes running
- Root cause: SSH-based worker detection timing out
- Solution: Check database for running chunks FIRST

Changes:
1. app/api/cluster/status/route.ts:
   - Query exploration database before SSH detection
   - If running chunks exist, mark workers 'active' even if SSH fails
   - Override worker status: 'offline' → 'active' when chunks running
   - Log: '✅ Cluster status: ACTIVE (database shows running chunks)'
   - Database is source of truth, SSH only for supplementary metrics

2. app/cluster/page.tsx:
   - Stop button ALREADY EXISTS (conditionally shown)
   - Shows Start when status='idle', Stop when status='active'
   - No code changes needed - fixed by status detection

Result:
- Dashboard now shows 'ACTIVE' with 2 workers (correct)
- Workers show 'active' status (was 'offline')
- Stop button automatically visible when cluster active
- System resilient to SSH timeouts/network issues

Verified:
- Container restarted: Nov 30 21:18 UTC
- API tested: Returns status='active', activeWorkers=2
- Logs confirm: Database-first logic working
- Workers confirmed running: 22+ processes on worker1, workers on worker2

run_sweep_vanilla_epyc.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+# Run vanilla v9 parameter sweep on EPYC server
+# Usage: ./run_sweep_vanilla_epyc.sh
+
+set -e
+
+# Activate virtual environment
+source .venv/bin/activate
+
+# Set PYTHONPATH to current directory
+export PYTHONPATH=$(pwd)
+
+echo "=== Starting RAW v9 Parameter Sweep ==="
+echo "Workers: 24 (EPYC optimized)"
+echo "Started: $(date)"
+echo "Output: sweep_v9_vanilla_epyc.csv"
+echo "Log: v9_vanilla_sweep.log"
+echo
+
+# Run in background with nohup
+nohup python scripts/run_backtest_sweep.py \
+  --csv data/solusdt_5m.csv \
+  --symbol SOLUSDT \
+  --timeframe 5m \
+  --flip-thresholds 0.4,0.5,0.6,0.7 \
+  --ma-gap-thresholds 0.20,0.30,0.40,0.50 \
+  --momentum-adx 18,21,24,27 \
+  --momentum-long-pos 60,65,70,75 \
+  --momentum-short-pos 20,25,30,35 \
+  --cooldown-bars 1,2,3,4 \
+  --momentum-spacing 2,3,4,5 \
+  --momentum-cooldown 1,2,3,4 \
+  --workers 24 \
+  > v9_vanilla_sweep.log 2>&1 &
+
+SWEEP_PID=$!
+echo "Sweep launched: PID $SWEEP_PID"
+echo "Monitor: tail -f v9_vanilla_sweep.log"
+echo
+sleep 3
+
+# Show initial output
+echo "=== First 30 lines of log ==="
+head -30 v9_vanilla_sweep.log
+
+echo
+echo "Sweep running in background (PID $SWEEP_PID)"
+echo "Results will be saved to: sweep_v9_vanilla_epyc.csv"