Add JSDoc documentation and file headers to all source files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

eslint.config.mjs

@@ -1,3 +1,13 @@
+// The Lucia project.
+// Copyright 2026-2026 DSP, inc.  All rights reserved.
+// Authors:
+//   imacat.yang@dsp.im (imacat), 2026/3/6
+/**
+ * @module eslint.config
+ *   ESLint flat configuration for Vue, Cypress, and
+ *   Prettier integration.
+ */
+
 import js from "@eslint/js";
 import pluginVue from "eslint-plugin-vue";
 import pluginCypress from "eslint-plugin-cypress";