feat: add audit_log_user table [D109] Layer 3 user operation audit

persona-brain-db/schema/13-audit-log-user.sql

@@ -0,0 +1,22 @@
+-- ============================================================
+-- 表13：audit_log_user（审计日志 · 用户操作 · append-only）
+-- 用途：普通用户级别的操作审计
+-- ============================================================
+
+CREATE TABLE IF NOT EXISTS audit_log_user (
+  log_id            INTEGER       PRIMARY KEY AUTOINCREMENT,
+  operation         VARCHAR(64)   NOT NULL,
+  actor_id          VARCHAR(64)   NOT NULL,        -- 用户ID
+  target_type       VARCHAR(32),
+  target_id         VARCHAR(64),
+  details           TEXT,                          -- JSON object
+  ip_address        VARCHAR(45),
+  user_agent        VARCHAR(256),
+  result            VARCHAR(16)   NOT NULL
+                    CHECK (result IN ('success', 'failure', 'pending')),
+  timestamp         TIMESTAMP     NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE INDEX IF NOT EXISTS idx_alu_actor ON audit_log_user(actor_id);
+CREATE INDEX IF NOT EXISTS idx_alu_operation ON audit_log_user(operation);
+CREATE INDEX IF NOT EXISTS idx_alu_timestamp ON audit_log_user(timestamp);