Feature request: configurable plugin parameters in /plugin interface

Summary

Plugins currently ship hooks and agents but have no mechanism for user-configurable settings. The settings.json in a plugin only supports the agent key. There's no way for a plugin to define parameters that users can toggle after installation through the /plugin interface.

Use case

A plugin ships a safety hook (e.g., blocking destructive git operations, rm -rf foo/, etc.) that should default to enabled. After the user builds trust with the plugin's process, they want to disable the hook. Today, this requires manually editing hooks/hooks.json at the plugin install path — not discoverable and not user-friendly.

Proposed behavior

1. Plugin manifest supports a config or settings section defining parameters with types, defaults, and descriptions
2. /plugin interface shows installed plugin settings and allows toggling
3. Plugin hooks and scripts can read these settings at runtime (e.g., via environment variable or JSON file)

Example manifest addition:

{
  "settings": {
    "block_destructive": {
      "type": "boolean",
      "default": true,
      "description": "Block destructive operations (force push, hard reset, recursive delete, etc.)"
    }
  }
}

Current workaround

Document manual editing of hooks.json at the plugin install path, or use environment variables — neither is discoverable through the plugin interface.