fix: recipe errors now show specific cause instead of generic 'connection error'

- PHP generateRecipeStream: wrap entire body in try/catch(\Throwable) to catch
  any PHP fatal/exception mid-stream and send it as a proper SSE error event
- PHP: curl timeout raised 60s→90s; capture curl errno/errmsg on failure
- PHP: HTTP error messages now include a human-readable status label
  (e.g. 'Quota API esaurita (429)', 'Nessuna risposta da Gemini (cURL: ...)')
- JS catch block: show err.message alongside error.connection so the actual
  JS network error (NetworkError, AbortError, etc.) is visible
- JS no-recipe+no-error path: show recipes.stream_interrupted instead of
  generic error.connection
- Translation: added recipes.stream_interrupted in it/en/de

assets/js/app.js

@@ -14443,7 +14443,8 @@ async function generateRecipe() {
                     showToast((errorEvent.error || t('recipes.generate_error')) + detail, 'error');
                 }
             } else {
-                showToast(t('error.connection'), 'error');
+                // Stream closed without recipe or error event — likely a server crash mid-stream
+                showToast(t('recipes.stream_interrupted'), 'error');
             }
         }
 
@@ -14451,7 +14452,9 @@ async function generateRecipe() {
         console.error('Recipe error:', err);
         document.getElementById('recipe-loading').style.display = 'none';
         document.getElementById('recipe-ask').style.display = '';
-        showToast(t('error.connection'), 'error');
+        // Show the actual JS error (e.g. NetworkError, AbortError, TypeError)
+        const errMsg = err?.message || String(err);
+        showToast(`${t('error.connection')}: ${errMsg}`, 'error');
     }
 }