Add typed JSON output to theme pull

[gonzaloriestra]

WHY are these changes introduced?

Related to https://github.com/shop/issues-develop/issues/23693

theme pull downloads files but does not expose a typed, discoverable JSON result for automation.

WHAT is this pull request doing?

Add --json with the local download path, remote theme metadata, and preview/editor links. Execution returns typed data; a presenter retains the existing success banner. The exported pull() adapter keeps its text behavior. Download progress uses typed side events in JSON mode.

Normal output:

The theme 'MyTheme' (#1) has been pulled.

Matching JSON:

{
  "path": "/path/to/theme",
  "theme": {
    "id": 1,
    "name": "MyTheme",
    "role": "unpublished",
    "processing": false,
    "shop": "example.myshopify.com",
    "editor_url": "https://example.myshopify.com/admin/themes/1/editor",
    "preview_url": "https://example.myshopify.com?preview_theme_id=1"
  }
}

Optional src metadata is included when available. The internal createdAtRuntime flag is not part of the public result.

Uses the draft multi-environment contract from the preceding PR: one array in requested order, environment names on successful results, failures on stderr, [] when none succeed, and unchanged exit behavior. Tests use real temporary files for downloads, deletion, and --nodelete.

How to manually test your changes?

pnpm shopify theme pull --help
pnpm shopify theme pull --json-schema
pnpm shopify theme pull --store example.myshopify.com --theme 1 --path ./theme --json
pnpm shopify theme pull --store example.myshopify.com --theme 1 --path ./theme --nodelete --json
pnpm shopify theme pull --environment staging --environment production --force --json

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• A single changeset for all theme migrations is added in the last PR, #8682.

[github-actions]

Differences in type declarations

We detected differences in the type declarations generated by Typescript for this branch compared to the baseline ('main' branch). Please, review them to ensure they are backward-compatible. Here are some important things to keep in mind:

• Some seemingly private modules might be re-exported through public modules.
• If the branch is behind main you might see odd diffs, rebase main into this branch.

New type declarations

We found no new type declarations in this PR

Existing type declarations

packages/cli-kit/dist/public/node/base-command.d.ts

@@ -35,6 +35,7 @@ declare abstract class BaseCommand extends Command {
         argv: string[];
     }>;
     protected environmentsFilename(): string | undefined;
+    protected validateNonTTYFlags(flags: FlagOutput): void;
     protected failMissingNonTTYFlags(flags: FlagOutput, requiredFlags: string[]): void;
     private failMissingNonTTYFlagRequirements;
     private applicableNonTTYFlagRequirements;