fix: make test button always visible in prompt editor

- Removed conditional hiding of test button (prompt?.slug)
- Button now always visible with helpful tooltip
- handleTest already has save-check logic

Improves discoverability of test functionality.

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

frontend/src/components/UnifiedPromptModal.jsx

@@ -691,7 +691,6 @@ export default function UnifiedPromptModal({ prompt, onSave, onClose }) {
           paddingTop: 16, borderTop: '1px solid var(--border)'
         }}>
           <div style={{ display: 'flex', gap: 8 }}>
-            {prompt?.slug && (
             <button
               className="btn"
               onClick={handleTest}
@@ -700,10 +699,10 @@ export default function UnifiedPromptModal({ prompt, onSave, onClose }) {
                 background: testing ? 'var(--surface)' : 'var(--accent)',
                 color: testing ? 'var(--text3)' : 'white'
               }}
+              title={!prompt?.slug ? 'Bitte erst speichern, dann testen' : 'Test mit Debug-Modus ausführen'}
             >
               {testing ? '🔬 Teste...' : '🔬 Test ausführen'}
             </button>
-            )}
             <button
               className="btn"
               onClick={handleExport}