Fix: Guard quick_commands against non-dict values

Problem

cli.py:6584 calls qcmd.get("type") on whatever value is in quick_commands — no validation that it's actually a dict. If a user has a string, int, or null value in their quick_commands config, all slash commands matching that key crash with AttributeError: 'str' object has no attribute 'get'.

Even worse, a broken quick_commands entry poisons any overlapping skill command, because quick_commands is checked BEFORE skill commands in the dispatch chain.

Reproduction

# ~/.hermes/config.yaml
quick_commands:
  foo: ''  # string instead of dict

Then /foo → Error: 'str' object has no attribute 'get'

Fix

Added isinstance(qcmd, dict) guard before accessing dict methods, matching the pattern already used in gateway/run.py:5214-5215. If the value is not a dict, we log a warning and fall through to plugin/skill command dispatch instead of crashing.

Testing

• Verified the fix applies cleanly on top of current origin/main
• The gateway already has this guard (lines 5214-5215), so this brings CLI parity with gateway

Fixes #18816