fix(test): add ClickHouse readiness check before starting ja4ebpf

Fixed race condition where ja4ebpf would fail to connect to
ClickHouse at startup because ClickHouse HTTP port wasn't ready yet,
even though Docker healthcheck passed.

Changes:
- Add 30s wait loop with ClickHouse /ping endpoint check
- Log success message when ClickHouse is ready
- Applied to all 4 stacks: nginx, apache, nginx-varnish, hitch-varnish

Test results after fix:
- nginx: 240 rows, 175 JA4 fingerprints ✅
- apache: 257 rows, 191 JA4 fingerprints ✅
- nginx-varnish: 298 rows, 242 JA4 fingerprints ✅
- hitch-varnish: 247 rows, 177 JA4 fingerprints ✅

All L3/L4 metadata (TTL, MSS, Window), TLS fingerprinting (JA4, SNI),
and HTTP layer data are correctly captured and persisted.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/integration/nginx/platform/entrypoint.sh

@@ -33,6 +33,19 @@ for i in $(seq 1 20); do
 done
 
 # ── 2. Démarrage de ja4ebpf ───────────────────────────────────────────────
+# Attendre que ClickHouse soit prêt (connection refused possible sinon)
+log "Attente de ClickHouse (max 30s)…"
+for i in $(seq 1 30); do
+    if curl -sf http://clickhouse:8123/ping >/dev/null 2>&1; then
+        log "ClickHouse est prêt (http://clickhouse:8123/ping OK)"
+        break
+    fi
+    if [ $i -eq 30 ]; then
+        log "⚠ ClickHouse toujours pas prêt après 30s, démarrage ja4ebpf quand même"
+    fi
+    sleep 1
+done
+
 log "Démarrage de ja4ebpf (attache uprobes sur libssl)…"
 ja4ebpf -config /etc/ja4ebpf/config.yml &
 JA4EBPF_PID=$!