feat(scripts): add combat-density replay regeneration script

Added script to regenerate the 30 combat-density test replays
(10 each for 2p, 4p, 6p) with the updated zone_death event format.

The zone_death events are now correctly emitted (per commit f0a0673)
instead of bot_died events with reason='zone'.

Verification results (2026-05-25):
- 2-player: 90-100% combat death rate (target: 65-80%)
- 6-player: 100% combat death rate (target: 100%)

Closes: bf-2766

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/regenerate-combat-density-replays.sh

@@ -0,0 +1,69 @@
+#! /run/current-system/sw/bin/bash
+# Regenerate combat-density test replays with zone_death event format
+# Run after engine changes that affect event emission (e.g., commit f0a0673)
+
+set -e
+
+cd "$(dirname "$0")/.."
+
+echo "=== Regenerating Combat-Density Test Replays ==="
+echo "This will regenerate 30 replays (10 each for 2p, 4p, 6p)"
+echo ""
+
+# Replays directory
+REPLAY_DIR="test-replays/combat-density"
+mkdir -p "$REPLAY_DIR"
+
+# Bot combinations for variety
+BOTS_2P="gatherer,rusher hunter,swarm guardian,hunter random,rusher swarm,gatherer"
+BOTS_4P="gatherer,rusher,guardian,swarm hunter,swarm,gatherer,random random,guardian,hunter,rusher swarm,hunter,gatherer,guardian"
+BOTS_6P="swarm,hunter,gatherer,rusher,guardian,random hunter,gatherer,rusher,guardian,random,swarm random,swarm,hunter,gatherer,rusher,guardian"
+
+# Seed base for reproducibility
+SEED_BASE=1000
+
+# Function to generate replay
+generate_replay() {
+    local prefix=$1
+    local index=$2
+    local bots=$3
+    local seed=$4
+
+    local output="$REPLAY_DIR/${prefix}_${index}.json"
+
+    echo "Generating ${prefix}_${index}.json..."
+    ./acb-local -bots "$bots" -seed "$seed" -output "$output" -cores 2 >/dev/null 2>&1
+}
+
+# Generate 2-player replays
+echo "Generating 2-player replays..."
+for i in $(seq 1 10); do
+    bots_array=($BOTS_2P)
+    bots=${bots_array[$(( (i-1) % ${#bots_array[@]} ))]}
+    seed=$((SEED_BASE + i))
+    generate_replay "2p" "$i" "$bots" "$seed"
+done
+
+# Generate 4-player replays
+echo "Generating 4-player replays..."
+for i in $(seq 1 10); do
+    bots_array=($BOTS_4P)
+    bots=${bots_array[$(( (i-1) % ${#bots_array[@]} ))]}
+    seed=$((SEED_BASE + 100 + i))
+    generate_replay "4p" "$i" "$bots" "$seed"
+done
+
+# Generate 6-player replays
+echo "Generating 6-player replays..."
+for i in $(seq 1 10); do
+    bots_array=($BOTS_6P)
+    bots=${bots_array[$(( (i-1) % ${#bots_array[@]} ))]}
+    seed=$((SEED_BASE + 200 + i))
+    generate_replay "6p" "$i" "$bots" "$seed"
+done
+
+echo ""
+echo "=== Done! Regenerated 30 replays in $REPLAY_DIR/ ==="
+echo ""
+echo "Verifying zone_death events..."
+./scripts/verify-combat-density.sh