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>
