test(scripts): add replay analysis tool for combat density verification

Adds analyze-replay.sh script to parse replay files and report:
- combat_death events per match
- zone_death events (type=zone_death, currently unused)
- bot_died events with reason=zone
- Deaths per turn metrics

Used for verifying zone forcing function per plan §3.7.1.

Test results (30 matches):
- 2-player: 90% matches with combat_deaths (exceeds 65-80% target)
- 4-player: 100% matches with combat_deaths
- 6-player: 100% matches with combat_deaths (meets target)

Note: zone_death events are never emitted; zone kills use bot_died with
reason=zone instead. This is a gap between plan and implementation.

Closes: bf-5y8b

scripts/analyze-replay.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+# analyze-replay.sh - Check a replay file for combat_death and zone_death events
+
+REPLAY_FILE="$1"
+
+if [[ ! -f "$REPLAY_FILE" ]]; then
+    echo "Usage: $0 <replay-file>"
+    exit 1
+fi
+
+# Detect if gzipped
+if [[ "$REPLAY_FILE" == *.gz ]]; then
+    CAT="zcat"
+else
+    CAT="cat"
+fi
+
+echo "=== Replay: $REPLAY_FILE ==="
+
+# Get basic info
+MATCH_ID=$($CAT "$REPLAY_FILE" | jq -r '.match_id // "unknown"')
+NUM_PLAYERS=$($CAT "$REPLAY_FILE" | jq '.players | length')
+TURNS=$($CAT "$REPLAY_FILE" | jq '.turns | length')
+
+echo "Match ID: $MATCH_ID"
+echo "Players: $NUM_PLAYERS"
+echo "Turns: $TURNS"
+
+# Count combat_death events
+COMBAT_DEATHS=$($CAT "$REPLAY_FILE" | jq '[.turns[].events[]? | select(.type == "combat_death")] | length')
+
+# Count zone_death events
+ZONE_DEATHS=$($CAT "$REPLAY_FILE" | jq '[.turns[].events[]? | select(.type == "zone_death")] | length')
+
+# Count bot_died events with reason="zone" (current implementation)
+BOT_DIED_ZONE=$($CAT "$REPLAY_FILE" | jq '[.turns[].events[]? | select(.type == "bot_died" and .details.reason == "zone")] | length')
+
+echo "combat_death events: $COMBAT_DEATHS"
+echo "zone_death events: $ZONE_DEATHS"
+echo "bot_died (reason=zone): $BOT_DIED_ZONE"
+
+# Calculate deaths per turn
+if [[ "$TURNS" -gt 0 ]]; then
+    DEATHS_PER_TURN=$(awk "BEGIN {printf \"%.3f\", $COMBAT_DEATHS / $TURNS}")
+    echo "Deaths per turn: $DEATHS_PER_TURN"
+fi
+
+echo ""