Phase 1 MVP - Complete implementation

- Login with JWT and refresh token rotation
- Dashboard with projects cards
- ProjectView with TreeView navigation
- DocumentView with markdown editor and auto-save
- Tag management (create, assign, remove)
- Dark mode CSS variables
- Security fixes applied (logout to backend, createDocument endpoint)

node_modules/postcss/lib/comment.js

@@ -0,0 +1,13 @@
+'use strict'
+
+let Node = require('./node')
+
+class Comment extends Node {
+  constructor(defaults) {
+    super(defaults)
+    this.type = 'comment'
+  }
+}
+
+module.exports = Comment
+Comment.default = Comment