Fix bare except clauses for better error handling

Replace 5 bare except clauses with 'except Exception:' to improve
error handling and prevent catching system exits and keyboard interrupts:

- gui.py:155 - Queue event processing
- setup_wizard.py:184 - API response parsing
- test_credentials.py:213 - Response JSON parsing
- test_credentials.py:240 - Error response parsing
- test_credentials.py:257 - Response text formatting

This change improves code quality and follows Python best practices
for exception handling.

setup_wizard.py

@@ -181,7 +181,7 @@ async def validate_perplexity_key(api_key, model="sonar-pro"):
                             print_warning(f"400 Fehler: {error_msg}")
                             print_info("Fahre trotzdem fort - bitte später manuell prüfen!")
                             return (True, False, model)
-                    except:
+                    except Exception:
                         print_warning(f"Unerwartete Antwort: {response.status_code}")
                         print_info("Fahre trotzdem fort - bitte später manuell prüfen!")
                         return (True, False, model)