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/Curl.php

@@ -24,23 +24,6 @@ class Curl
         $this->ch = curl_init();
     }
 
-    public function useCookies()
-    {
-        $cookiesFile = tempnam(sys_get_temp_dir(), 'virtfusion_cookies');
-        $this->defaultOptions[CURLOPT_COOKIEFILE] = $cookiesFile;
-        $this->defaultOptions[CURLOPT_COOKIEJAR] = $cookiesFile;
-    }
-
-    public function setLog()
-    {
-        $log = fopen(__DIR__ . '/CURL.log', 'a');
-        if ($log) {
-            fwrite($log, str_repeat('=', 80) . PHP_EOL);
-            $this->addOption(CURLOPT_STDERR, $log);
-            $this->addOption(CURLOPT_VERBOSE, true);
-        }
-    }
-
     /**
      * @param $name
      * @param $value
@@ -166,15 +149,6 @@ class Curl
         return $this->send('POST', $url);
     }
 
-    /**
-     * @param null $url
-     * @return bool|string|void
-     */
-    public function head($url = null)
-    {
-        return $this->send('HEAD', $url);
-    }
-
     /**
      * @param false $param
      * @return mixed|null
@@ -202,16 +176,4 @@ class Curl
         }
     }
 
-    /**
-     * @param false $param
-     * @return mixed|null
-     */
-    public function getHeadersData($param = false)
-    {
-        if ($param) {
-            return $this->getDataItem('data', $param);
-        }
-
-        return $this->data['data'];
-    }
 }