feat(secrets-mcp): 审计页、audit_log user_id、OAuth 登录与仪表盘 footer

- audit_log 增加 user_id；业务写审计透传 user_id
- Web /audit 与侧边栏；Dashboard 版本 footer 贴底（margin-top: auto）
- 停止 API Key 鉴权成功写入登录审计
- 文档、CI、release-check 配套更新

Made-with: Cursor

crates/secrets-core/src/db.rs

@@ -67,6 +67,7 @@ pub async fn migrate(pool: &PgPool) -> Result<()> {
         -- ── audit_log: append-only operation log ─────────────────────────────────
         CREATE TABLE IF NOT EXISTS audit_log (
             id          BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
+            user_id     UUID,
             action      VARCHAR(32)  NOT NULL,
             namespace   VARCHAR(64)  NOT NULL,
             kind        VARCHAR(64)  NOT NULL,
@@ -76,8 +77,10 @@ pub async fn migrate(pool: &PgPool) -> Result<()> {
             created_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW()
         );
 
+        ALTER TABLE audit_log ADD COLUMN IF NOT EXISTS user_id UUID;
         CREATE INDEX IF NOT EXISTS idx_audit_log_created  ON audit_log(created_at DESC);
         CREATE INDEX IF NOT EXISTS idx_audit_log_ns_kind  ON audit_log(namespace, kind);
+        CREATE INDEX IF NOT EXISTS idx_audit_log_user_id  ON audit_log(user_id) WHERE user_id IS NOT NULL;
 
         -- ── entries_history ───────────────────────────────────────────────────────
         CREATE TABLE IF NOT EXISTS entries_history (