fix(config): log warning instead of silently swallowing config.yaml errors (#2683)

A bare `except Exception: pass` meant any YAML syntax error, bad value,
or unexpected structure in config.yaml was silently ignored and the
gateway fell back to .env / gateway.json without any indication.
Users had no way to know why their config changes had no effect.

Co-authored-by: sprmn24 <oncuevtv@gmail.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

gateway/config.py

@@ -523,8 +523,13 @@ def load_gateway_config() -> GatewayConfig:
                     os.environ["DISCORD_FREE_RESPONSE_CHANNELS"] = str(frc)
                 if "auto_thread" in discord_cfg and not os.getenv("DISCORD_AUTO_THREAD"):
                     os.environ["DISCORD_AUTO_THREAD"] = str(discord_cfg["auto_thread"]).lower()
-    except Exception:
-        pass
+    except Exception as e:
+        logger.warning(
+            "Failed to process config.yaml — falling back to .env / gateway.json values. "
+            "Check %s for syntax errors. Error: %s",
+            _home / "config.yaml",
+            e,
+        )
 
     config = GatewayConfig.from_dict(gw_data)