fix(settings): remove pattern attribute blocking Claude Code version save

The `pattern="\d+\.\d+\.\d+"` on the min_claude_code_version input caused
the browser's native HTML5 form validation to silently block form submission
when the value was invalid or when the hidden gateway tab was active. This
resulted in no network request being sent when clicking Save on any tab.

Backend already validates semver format and returns a proper 400 error,
so the frontend pattern attribute is redundant.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/views/admin/SettingsView.vue

@@ -1037,7 +1037,6 @@
                 type="text"
                 class="input max-w-xs font-mono text-sm"
                 :placeholder="t('admin.settings.claudeCode.minVersionPlaceholder')"
-                pattern="\d+\.\d+\.\d+"
               />
               <p class="mt-1.5 text-xs text-gray-500 dark:text-gray-400">
                 {{ t('admin.settings.claudeCode.minVersionHint') }}