feat(monitoring): add combat death rate analysis script

Added analyze-combat-deaths.sh script to track combat_death rate
across replay files. Reports percentage of matches with combat_deaths
by player count and average deaths per match.

Usage:
  ./scripts/analyze-combat-deaths.sh /path/to/replays

For production monitoring, download replays from R2 and analyze:
  aws s3 sync s3://acb-replays /tmp/replays
  ./scripts/analyze-combat-deaths.sh /tmp/replays

Full database integration (persist combat_deaths to DB, dashboard UI)
left for future work as combat_deaths are already tracked in replay files.

Closes: bf-38ts

scripts/analyze-combat-deaths.sh

@@ -0,0 +1,93 @@
+#!/bin/bash
+# Analyze combat_death rate from replay files
+# Usage: ./scripts/analyze-combat-deaths.sh <replay-files-directory>
+
+set -e
+
+REPLAY_DIR="${1:-/tmp/replays}"
+
+if [ ! -d "$REPLAY_DIR" ]; then
+  echo "Error: Replay directory not found: $REPLAY_DIR"
+  echo "Usage: $0 <replay-files-directory>"
+  exit 1
+fi
+
+echo "=== Combat Death Rate Analysis ==="
+echo "Analyzing replays in: $REPLAY_DIR"
+echo
+
+# Count replays with combat_deaths by player count
+analyze_replays() {
+  local player_count=$1
+  local total=0
+  local with_deaths=0
+  local total_deaths=0
+
+  for replay in "$REPLAY_DIR"/*.json "$REPLAY_DIR"/*.json.gz 2>/dev/null; do
+    [ -f "$replay" ] || continue
+
+    # Check player count
+    local pc=$(python3 -c "
+import json, sys
+try:
+    if '$replay'.endswith('.gz'):
+        import gzip
+        f = gzip.open('$replay', 'rt')
+    else:
+        f = open('$replay')
+    r = json.load(f)
+    print(len(r.get('players', [])))
+except Exception as e:
+    print(0)
+" 2>/dev/null)
+
+    if [ "$pc" != "$player_count" ]; then
+      continue
+    fi
+
+    total=$((total + 1))
+
+    # Count combat_deaths
+    local deaths=$(python3 -c "
+import json, sys
+try:
+    if '$replay'.endswith('.gz'):
+        import gzip
+        f = gzip.open('$replay', 'rt')
+    else:
+        f = open('$replay')
+    r = json.load(f)
+    deaths = 0
+    for t in r.get('turns', []):
+        for e in t.get('events', []):
+            if e.get('type') == 'combat_death':
+                deaths += 1
+    print(deaths)
+except Exception as e:
+    print(0)
+" 2>/dev/null)
+
+    if [ "$deaths" -gt 0 ]; then
+      with_deaths=$((with_deaths + 1))
+      total_deaths=$((total_deaths + deaths))
+    fi
+  done
+
+  if [ $total -eq 0 ]; then
+    echo "No $player_count-player replays found"
+  else
+    local rate=$((with_deaths * 100 / total))
+    local avg=$(python3 -c "print($total_deaths / $total)")
+    echo "$player_count-player: $with_deaths/$total ($rate%) with combat_deaths, avg $avg per match"
+  fi
+}
+
+# Analyze by player count
+for pc in 2 3 4 6; do
+  analyze_replays $pc
+done
+
+echo
+echo "To monitor production matches:"
+echo "1. Download replays from R2: aws s3 sync s3://acb-replays /tmp/replays"
+echo "2. Run: ./scripts/analyze-combat-deaths.sh /tmp/replays"