feat: v0.4.0 — Apache service stack, shell access, log viewer, changelog

Service stack (backend):
- webserver.ts rewritten: apache2/php-fpm routes replacing nginx; per-account
  Apache log endpoint; PHP-FPM reload per version; apache2ctl configtest/reload
- accounts.ts: added PUT /:id/shell to toggle /bin/bash vs /usr/sbin/nologin,
  runs usermod -s and writes audit log

New UI features (nixserver):
- ShellAccess page: grant/revoke SSH access per account via AccountPicker
- ApacheLogs page: live log viewer (access/error) per account; replaces stub
- NginxLogs: re-exports ApacheLogs (NixPanel uses Apache, not NGINX)
- WebServer page: shows apache2, php8.2-fpm, php8.3-fpm status with reload
  buttons; config test; Apache log viewer

Bug fixes:
- Accounts.tsx: Lucide icon size prop type widened (string|number); removed
  unused Users import; dropped duplicate NGINX log card
- Removed soon badge from ShellAccess and ApacheLogs entries

Project:
- CHANGELOG.md created with full history from 0.2.x through 0.4.0
- All packages bumped from 0.3.2 to 0.4.0

package.json

@@ -1,6 +1,6 @@
 {
   "name": "nixpanel-server",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "private": true,
   "workspaces": [
     "server",