chore: remove dead top-level toolsets config key

The top-level 'toolsets' key in config.yaml was never read at runtime.
Tool selection uses platform_toolsets (per-platform) or the --toolsets
CLI flag. The key existed in load_cli_config() defaults and the example
config as 'toolsets: [all]', misleading users into thinking it
controlled tool availability.

- Remove from load_cli_config() hardcoded defaults
- Remove from hermes config show output
- Replace in cli-config.yaml.example with deprecation note pointing
  to platform_toolsets and hermes tools

cli.py

@@ -211,7 +211,7 @@ def load_cli_config() -> Dict[str, Any]:
                 "hype": "YOOO LET'S GOOOO!!! I am SO PUMPED to help you today! Every question is AMAZING and we're gonna CRUSH IT together! This is gonna be LEGENDARY! ARE YOU READY?! LET'S DO THIS!",
             },
         },
-        "toolsets": ["all"],
+
         "display": {
             "compact": False,
             "resume_display": "full",