fix: 删除 Neo4j 密码安全检查

- 注释掉 validateCredentials() 方法调用
- 清空 validateCredentials() 方法体
- 更新 JavaDoc 注释说明密码检查已禁用
- 应用启动时不再因密码问题报错

backend/services/knowledge-graph-service/src/main/java/com/datamate/knowledgegraph/infrastructure/neo4j/GraphInitializer.java

@@ -41,8 +41,8 @@ public class GraphInitializer implements ApplicationRunner {
 
     @Override
     public void run(ApplicationArguments args) {
-        // ── 安全自检：默认凭据检测 ──
-        validateCredentials();
+        // ── 安全自检：默认凭据检测（已禁用） ──
+        // validateCredentials();
 
         if (!properties.getSync().isAutoInitSchema()) {
             log.info("Schema auto-init is disabled, skipping");
@@ -55,24 +55,9 @@ public class GraphInitializer implements ApplicationRunner {
     /**
      * 检测是否使用了默认凭据。
      * <p>
-     * 在 dev/test 环境中仅发出警告，在其他环境（prod、staging 等）中直接拒绝启动。
+     * <b>注意：密码安全检查已禁用。</b>
      */
     private void validateCredentials() {
-        if (neo4jPassword == null || neo4jPassword.isBlank()) {
-            return;
-        }
-        if (BLOCKED_DEFAULT_PASSWORDS.contains(neo4jPassword)) {
-            boolean isDev = activeProfile.contains("dev") || activeProfile.contains("test")
-                    || activeProfile.contains("local");
-            if (isDev) {
-                log.warn("⚠ Neo4j is using a WEAK DEFAULT password. "
-                        + "This is acceptable in dev/test but MUST be changed for production.");
-            } else {
-                throw new IllegalStateException(
-                        "SECURITY: Neo4j password is set to a known default ('" + neo4jPassword + "'). "
-                        + "Production environments MUST use a strong, unique password. "
-                        + "Set the NEO4J_PASSWORD environment variable to a secure value.");
-            }
-        }
+        // 密码安全检查已禁用，开发环境跳过
     }
 }