[JS] fix genkitx-* plugins for `next` (0.9) release

[pavelgj]

Plugin migration guide:

Update deps:

Before:

  "dependencies": {
   ...
    "zod": "^3.23.8"
  },
  "peerDependencies": {
    "@genkit-ai/ai": "^0.5.0",
    "@genkit-ai/core": "^0.5.0"
  },

After:

  "dependencies": {
    ...
  },
  "peerDependencies": {
    "genkit": "^0.9 | ^1.0",
  },

Note that dependency on zod is gone. Zod is now reexported via genkit package. Import it from there. See below.

until 0.9 is published may need:

  "dependencies": {
    ...
  },
  "peerDependencies": {
    "genkit": ">0.9.0-dev.0 | ^0.9 | ^1.0",
  },

Before:

import { genkitPlugin, type Plugin } from '@genkit-ai/core';
import { defineModel } from '@genkit-ai/ai/model';
import { defineEmbedder } from '@genkit-ai/ai/embedder';
import { z } from 'zod';

export const myPlugin: Plugin<[MyPluginOptions] | []> = genkitPlugin(
  'myPlugin',
  async (options?: MyPluginOptions) => {
    return {
      models:[defineModel(...), defineModel(...) ],
      embedders: [ defineEmbedder(...), defineEmbedder(...) ],
    };
  }
);

After:

import { Genkit, z } from 'genkit';
import { GenkitPlugin, genkitPlugin } from 'genkit/plugin';

export function myPlugin(options?: MyPluginOptions) {
  return genkitPlugin('myPlugin', async (ai: Genkit) => {
    ai.defineModel(...);
    ai.defineEmbedder(...)
    // ....
  });
}

[pavelgj]

@cabljac genkit@0.9.0-dev.1 is published to npm, that should unblock plugin conversion work.

https://www.npmjs.com/package/genkit/v/0.9.0-dev.1

[pavelgj]

I also added migration instructions to the description.

[cabljac]

and the main ones are OpenAI, Anthropic, Cohere?