Asset pipeline flow for hosted static app

[elanalynn]

DEPENDS ON https://github.com/shop/world/pull/382743 TO SHIP FIRST

WHY are these changes introduced?

Related to Hosted app project.

Related to https://github.com/shop/world/pull/382743

Closes https://github.com/shop/issues-admin-extensibility/issues/2186

WHAT is this pull request doing?

This PR introduces the asset pipeline flow for hosted static apps, enabling static asset copying during the build process.

• New hosted_app specification (app_config_hosted_app_home.ts): Adds a configuration extension specification for hosted apps with a static_root field
• New static_app build mode: Extends the build config modes to include static_app, which triggers static asset copying
• Enhanced config extension specifications:
  • Added optional buildConfig and copyStaticAssets parameters to createConfigExtensionSpecification()
  • Config extensions can now define custom build behavior

How it works

When a hosted app defines a static_root in its configuration:

1. The hosted_app specification is loaded with build mode static_app
2. During build, copyStaticAssets() is invoked
3. Contents from the configured static_root directory are copied to the output directory

How to test your changes?

• Configure a hosted app with static_root pointing to a static assets directory
• Run shopify app deploy and verify assets are copied to the output directory - .shopify/deploy-bundle
• Verify deploy works when static_root is not specified
• TODO: Verify appropriate error handling when source directory doesn't exist

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix
• Existing analytics will cater for this addition
• PR includes analytics changes to measure impact

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	78.9%	14565/18459
🟡	Branches	73.24%	7227/9868
🟡	Functions	79.1%	3706/4685
🟡	Lines	79.25%	13771/17376

Test suite run success

3780 tests passing in 1460 suites.

Report generated by 🧪jest coverage report action from ae0d089

[alfonso-noriega]

• Abstract build steps to externalize the build configuration #6842
• Asset pipeline flow for hosted static app #6806 👈 (View in Graphite)
• main

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[github-actions]

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