feat(cli,gateway): add user-defined quick commands that bypass agent loop

Implements config-driven quick commands for both CLI and gateway that
execute locally without invoking the LLM.

Config example (~/.hermes/config.yaml):
  quick_commands:
    limits:
      type: exec
      command: /home/user/.local/bin/hermes-limits
    dn:
      type: exec
      command: echo daily-note

Changes:
- hermes_cli/config.py: add quick_commands: {} default
- cli.py: check quick_commands before skill commands in process_command()
- gateway/run.py: check quick_commands before skill commands in _handle_message()
- tests/test_quick_commands.py: 11 tests covering exec, timeout, unsupported type, missing command, priority over skills

Closes #744

hermes_cli/config.py

@@ -147,6 +147,8 @@ DEFAULT_CONFIG = {
 
     # Permanently allowed dangerous command patterns (added via "always" approval)
     "command_allowlist": [],
+    # User-defined quick commands that bypass the agent loop (type: exec only)
+    "quick_commands": {},
 
     # Config schema version - bump this when adding new required fields
     "_config_version": 5,