Extend `run` and `runStreamed` input to be either a `string` or
structured input. A structured input is an array of text parts and/or
image paths, which will then be fed to the CLI through the `--image`
argument. Text parts are combined with double newlines. For instance:
```ts
const turn = await thread.run([
{ type: "text", text: "Describe these screenshots" },
{ type: "local_image", path: "./ui.png" },
{ type: "local_image", path: "./diagram.jpg" },
{ type: "text", text: "Thanks!" },
]);
```
Ends up launching the CLI with:
```
codex exec --image foo.png --image bar.png "Describe these screenshots\n\nThanks!"
```
The complete `Input` type for both function now is:
```ts
export type UserInput =
| {
type: "text";
text: string;
}
| {
type: "local_image";
path: string;
};
export type Input = string | UserInput[];
```
This brings the Codex SDK closer to feature parity with the CLI.
Adresses #5280 .
3282e86a60