fix: bootstrap OIDC config — add retry and null guard

Phase 7 server health check failed intermittently due to timing.
Add 3-attempt retry loop with 2s sleep. Guard against jq returning
literal "null" string for TRAD_SECRET. Add debug logging for both
preconditions.

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

docker/logto-bootstrap.sh

@@ -171,6 +171,7 @@ else
   }")
   TRAD_ID=$(echo "$TRAD_RESPONSE" | jq -r '.id')
   TRAD_SECRET=$(echo "$TRAD_RESPONSE" | jq -r '.secret')
+  [ "$TRAD_SECRET" = "null" ] && TRAD_SECRET=""
   log "Created Traditional app: $TRAD_ID"
 fi
 
@@ -415,7 +416,15 @@ fi
 # PHASE 7: Configure cameleer3-server OIDC
 # ============================================================
 
-SERVER_HEALTHY=$(curl -sf "${SERVER_ENDPOINT}/api/v1/health" 2>/dev/null && echo "yes" || echo "no")
+SERVER_HEALTHY="no"
+for i in 1 2 3; do
+  if curl -sf "${SERVER_ENDPOINT}/api/v1/health" >/dev/null 2>&1; then
+    SERVER_HEALTHY="yes"
+    break
+  fi
+  sleep 2
+done
+log "Phase 7 check: SERVER_HEALTHY=$SERVER_HEALTHY, TRAD_SECRET length=${#TRAD_SECRET}"
 
 if [ "$SERVER_HEALTHY" = "yes" ] && [ -n "$TRAD_SECRET" ]; then
   log "Configuring cameleer3-server OIDC..."