Add WebDAV support via Apache mod_dav

Backend:
- WebDAV config managed at /etc/apache2/conf-available/micronas-webdav.conf
  with BEGIN/END markers per share; reload apache2 on every write
- htpasswd file at /etc/micronas-webdav.passwd synced automatically on
  create_user, change_password, delete_user
- Full CRUD: POST/PATCH/DELETE /api/share/webdav[/<name>]
- _validate_webdav_users(): space-separated, no @group (not supported by Apache)
- Fix: _validate_users() now allows @groupname for SMB (was incorrectly rejected)
- Dashboard: apache2 status + restart button; webdav shares in /api/dashboard

Frontend:
- WebDAV tab: create form + table with clickable access URLs
- Edit modal supports 'webdav' type (name, path, users, permissions section)
- badge-webdav CSS class (green tint) in app.css
- dashboard.js renders badge-<type> dynamically (smb/nfs/webdav)

Docs: README WebDAV mount guide (Linux davfs2, Windows, Mac), PLANNING phase 4

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

templates/index.html

@@ -88,6 +88,9 @@
         <li class="nav-item">
             <button class="nav-link" data-bs-toggle="tab" data-bs-target="#nfs" type="button">NFS Exports</button>
         </li>
+        <li class="nav-item">
+            <button class="nav-link" data-bs-toggle="tab" data-bs-target="#webdav" type="button">WebDAV</button>
+        </li>
         <li class="nav-item">
             <button class="nav-link" data-bs-toggle="tab" data-bs-target="#users" type="button">Users</button>
         </li>
@@ -98,7 +101,7 @@
         <!-- DASHBOARD -->
         <div class="tab-pane fade show active" id="dashboard">
             <div class="row g-3 mb-4">
-                <div class="col-6 col-md-2">
+                <div class="col-4 col-md-2">
                     <div class="card h-100">
                         <div class="card-body py-3 px-3">
                             <div class="card-label">smbd</div>
@@ -108,7 +111,7 @@
                         </div>
                     </div>
                 </div>
-                <div class="col-6 col-md-2">
+                <div class="col-4 col-md-2">
                     <div class="card h-100">
                         <div class="card-body py-3 px-3">
                             <div class="card-label">nfsd</div>
@@ -118,6 +121,16 @@
                         </div>
                     </div>
                 </div>
+                <div class="col-4 col-md-2">
+                    <div class="card h-100">
+                        <div class="card-body py-3 px-3">
+                            <div class="card-label">apache2</div>
+                            <div class="d-flex align-items-center mt-1" id="statusApache2">
+                                <span class="dot dot-red"></span><span class="small">…</span>
+                            </div>
+                        </div>
+                    </div>
+                </div>
                 <div class="col-12 col-md-8">
                     <div class="card h-100">
                         <div class="card-body py-3 px-3">
@@ -211,6 +224,32 @@
             </div>
         </div>
 
+        <!-- WEBDAV -->
+        <div class="tab-pane fade" id="webdav">
+            <div class="fw-semibold mb-3">Add WebDAV Share</div>
+            <div class="row g-2 mb-4">
+                <div class="col-md-2"><input type="text" id="webdavName" class="form-control" placeholder="Share name"></div>
+                <div class="col-md-4"><input type="text" id="webdavPath" class="form-control" placeholder="/srv/data"></div>
+                <div class="col-md-3"><input type="text" id="webdavUsers" class="form-control" placeholder="alice bob (empty = all)"></div>
+                <div class="col-md-3"><button type="button" class="btn btn-success w-100" onclick="addWebDAVShare()">Add</button></div>
+            </div>
+            <div class="fw-semibold mb-2">Shares</div>
+            <div class="table-responsive">
+                <table class="table table-striped mb-0">
+                    <thead><tr><th>Name</th><th>Path</th><th>Users</th><th>URL</th><th>Actions</th></tr></thead>
+                    <tbody id="webdavTableBody">
+                        <tr><td colspan="5" style="color:var(--muted)">Loading…</td></tr>
+                    </tbody>
+                </table>
+            </div>
+            <div class="mt-3" style="font-size:.82rem; color:var(--muted)">
+                Requires <code>apache2</code> + <code>apache2-utils</code> installed and
+                <code>mod_dav</code> / <code>mod_dav_fs</code> enabled.
+                Shares are served at <code>http://&lt;server-ip&gt;/dav/&lt;name&gt;</code>.
+                User passwords are synced automatically from the Users tab.
+            </div>
+        </div>
+
         <!-- USERS -->
         <div class="tab-pane fade" id="users">
             <div class="fw-semibold mb-3">Create User</div>