feat(collection-index): Add Oh My Posh Dev Container Features

[iAmBipinPaul]

• Add Oh My Posh Dev Container Features entry to collection index
• Include maintainer information (Bipin Paul)
• Add contact link to GitHub issues repository
• Add repository reference to iambipinpaul/devcontainer-features
• Add OCI reference for ghcr.io/iambipinpaul/devcontainer-features

What type of PR is this?

• Add a new dev container collection
• Update to an existing dev container collection
• Documentation/spec update
• Other containers.dev site update (UX, layout, etc)

Related Issues

• Related Issue #
• Closes

Description

This PR adds the Oh My Posh Dev Container Features collection to the collection index. Oh My Posh is a prompt theme engine for any shell with support for custom themes, providing enhanced terminal customization for development containers.

The feature supports:

• Installation of Oh My Posh with configurable versions
• Theme configuration via URL or file path
• Support for both bash and zsh shells
• 200+ built-in themes from the official Oh My Posh repository

Collection checklist

If your PR contributes a new collection, please utilize this checklist:

• Collection name
• Maintainer name
• Maintainer contact link (i.e. link to a GitHub repo, email)
• Repository URL
• OCI Reference
• I acknowledge that this collection provides new functionality, distinct from the existing collections part of this index.