完善 readiness、发布追溯与敏感治理（07-15-production-trust-closeout-cleanup）

server/src/config.js

@@ -11,6 +11,11 @@ function requiredEnv(name) {
   return value;
 }
 
+function normalizeBuildSha(value) {
+  const sha = String(value || "").trim().toLowerCase();
+  return /^[0-9a-f]{7,64}$/.test(sha) ? sha.slice(0, 12) : "unknown";
+}
+
 function getConfig() {
   const nodeEnv = process.env.NODE_ENV ?? "development";
   const serverRoot = path.resolve(__dirname, "..");
@@ -21,6 +26,7 @@ function getConfig() {
     nodeEnv,
     port: Number(process.env.PORT ?? 3000),
     host: process.env.HOST ?? "0.0.0.0",
+    buildSha: normalizeBuildSha(process.env.BUILD_SHA),
 
     metricsEnabled: process.env.METRICS_ENABLED !== "false",