Add the ability to extend GenAIScript's core contexts (global, host, workspace, parsers) through a plugin system, enabling users to add custom functionality without modifying core code.

Motivation

Currently, extending GenAIScript requires modifying core files or creating wrapper implementations. Users should be able to:

• Add custom workspace file parsers (e.g., .proto, .graphql, custom formats)
• Extend the global context with project-specific utilities
• Register custom host capabilities (e.g., database connections, API clients)
• Add domain-specific tools and helpers

Proposed Solution

Allow plugins to be registered via configuration file:

{
  "plugins": ["./plugins/my-plugin.js", "genaiscript-plugin-database"]
}

Plugin API:

import { plugin } from "genaiscript/plugin"

export default plugin({
  name: 'my-plugin',
  setup(extend, options) {
    extend(({ global, host, workspace, parsers }) => {
      // Extend global context
      global.defTask = (name, fn) => { /* ... */ }
      
      // Add custom parsers
      parsers.readProto = async (file) => { /* ... */ }
      
      // Extend workspace
      workspace.queryDatabase = async (sql) => { /* ... */ }
      
      // Add host capabilities  
      host.customService = () => { /* ... */ }
    })
  }
})

Benefits

• Modularity: Keep custom code separate from core framework
• Reusability: Share plugins across projects or publish to npm
• Type Safety: Plugins can provide TypeScript definitions
• Declarative: Clear plugin API with standardized structure
• Composable: Multiple plugins can coexist

Thoughts

1. Should plugins support async initialization?
2. How to handle plugin conflicts/priorities when multiple plugins extend the same context?
3. Should plugins have access to all framework internals or sandboxed APIs only?
4. Should there be lifecycle hooks (beforeRun, afterRun, etc.)?