feat: add L/S ratio collector service for top_acct and global ratios

Collect top trader account L/S ratio and global L/S ratio every 15 minutes
for XRP, BTC, ETH (6 API calls/cycle) and persist to per-symbol parquet files.
Deployed as a separate Docker service reusing the bot image.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/collect_ls_ratio_loop.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+# 15분 경계에 맞춰 collect_ls_ratio.py를 반복 실행한다.
+# Docker 컨테이너 entrypoint용.
+
+set -e
+
+echo "[collect_ls_ratio] Starting loop (interval: 15m)"
+
+while true; do
+    # 현재 분/초를 기준으로 다음 15분 경계(00/15/30/45)까지 대기
+    now_min=$(date -u +%M | sed 's/^0//')
+    now_sec=$(date -u +%S | sed 's/^0//')
+    # 다음 15분 경계까지 남은 분
+    remainder=$((now_min % 15))
+    wait_min=$((15 - remainder))
+    # 초 단위로 변환 (경계 직후 10초 여유)
+    wait_sec=$(( wait_min * 60 - now_sec + 10 ))
+    if [ "$wait_sec" -le 10 ]; then
+        wait_sec=$((wait_sec + 900))
+    fi
+
+    echo "[collect_ls_ratio] Next run in ${wait_sec}s ($(date -u))"
+    sleep "$wait_sec"
+
+    echo "[collect_ls_ratio] Running collection... ($(date -u))"
+    python scripts/collect_ls_ratio.py || echo "[collect_ls_ratio] ERROR: collection failed"
+done