release: v0.3 – organizations, assignments, themes, search, export

- Organizations decide who sees whom (private / organizations / open),
  owner-only sharing, rights follow visibility
- Task assignment in shared lists, unified people search, avatar stacks,
  CountBadge, tinted theme colours
- Custom CSS themes per user, legal notices, "Über MindSift", Unlicense
- SMTP hardening with per-step errors and skip-verify
- Global FTS5 search with Cmd+K, full emoji picker, Markdown/Obsidian export,
  new help page, demo mode resets on start
- Package version 0.3.0, README badge/screenshots renewed

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "mindsift-frontend",
   "private": true,
-  "version": "0.2.0",
+  "version": "0.3.0",
   "license": "Unlicense",
   "type": "module",
   "scripts": {