Add wimtools and startnet.cmd editor for boot.wim modification

- Added wimtools to offline packages and playbook verification
- Webapp startnet.cmd editor: extract, view, edit, save back to boot.wim
- Uses wimextract/wimupdate for in-place WIM modification
- Dark-themed code editor with tab support and common command reference

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

webapp/templates/base.html

@@ -137,6 +137,12 @@
     <div class="nav-section-divider"></div>
     <div class="sidebar-heading">Tools</div>
     <ul class="nav flex-column">
+      <li class="nav-item">
+        <a class="nav-link {% if request.endpoint == 'startnet_editor' %}active{% endif %}"
+           href="{{ url_for('startnet_editor') }}">
+          <i class="bi bi-terminal"></i> startnet.cmd
+        </a>
+      </li>
       <li class="nav-item">
         <a class="nav-link {% if request.endpoint == 'clonezilla_backups' %}active{% endif %}"
            href="{{ url_for('clonezilla_backups') }}">