fix: remove dead code, update stale versions, tag-based release workflow

Dead code removed:
- Module.php: remove addIPv4() method (no endpoint, feature removed per CLAUDE.md)
- Curl.php: remove useCookies(), setLog() (security risk — wrote tokens to
  web-accessible CURL.log), head(), getHeadersData() — all unused
- module.css: remove .vf-button, .vf-button-small (never referenced in DOM)
- module.css: remove vestigial #vf-data-server-traffic-sep rule
- module.css: merge duplicate #vf-server-info-error declarations
- publish-release.yml: remove dead version.json generation step (nothing reads it)

Fixes:
- AdminHTML.php: update stale cache version strings 20260207 → 20260319
- hooks.php: update stale keygen.js version string
- hooks.php: remove unused `use WHMCS\User\User` import
- ConfigureService.php: remove unused `use JsonException` import
- module.css: fix .vf-os-details class selector → #vf-os-details ID selector
- client.php + admin.php: reuse existing $vf instead of new Module()
- Module.php: use Cache::forget() instead of forgetPattern() for known key
  (forgetPattern is a no-op on filesystem cache fallback)

Workflow:
- Rewrite publish-release.yml: tag-based triggers only (no automatic releases)
- Triggers on push of v* tags, creates GitHub release with auto-generated notes
- Uses softprops/action-gh-release@v2 — compatible with both Gitea and GitHub

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/servers/VirtFusionDirect/lib/AdminHTML.php

@@ -35,8 +35,8 @@ EOT;
     {
         $systemUrl = htmlspecialchars($systemUrl, ENT_QUOTES, 'UTF-8');
         return <<<EOT
-            <link href="${systemUrl}modules/servers/VirtFusionDirect/templates/css/module.css?v=20260207" rel="stylesheet">
-            <script src="${systemUrl}modules/servers/VirtFusionDirect/templates/js/module.js?v=20260207"></script>
+            <link href="${systemUrl}modules/servers/VirtFusionDirect/templates/css/module.css?v=20260319" rel="stylesheet">
+            <script src="${systemUrl}modules/servers/VirtFusionDirect/templates/js/module.js?v=20260319"></script>
             <div id="vf-loader" class="vf-loader">
                <div id="vf-loading"></div>
             </div>