docs(mini-apps): multiple pages contain TODO stubs with no content

[Sertug17]

Bug

Several Mini Apps documentation pages contain only TODO comments with no actual content, making them unhelpful for developers.

Affected Pages

1. docs/mini-apps/troubleshooting/error-handling.mdx — TODO: Provide guidance on handling errors from hooks, network issues, and manifest/metadata failures.
2. docs/mini-apps/quality-and-publishing/overview.mdx — TODO: Write end-to-end guidance for becoming Featured
3. docs/mini-apps/quality-and-publishing/submission-guidelines.mdx — TODO: Define required assets (icons, hero, screenshots), URLs, manifest checks
4. docs/mini-apps/quality-and-publishing/quality-bar.mdx — TODO: Draft the full Quality Bar article

Impact

Developers visiting these pages find no useful content, which harms the documentation experience.

Steps to Reproduce

1. Visit any of the affected pages on docs.base.org
2. See only a TODO comment with no content