Follow up polyglot gaps in 'Aspireify an existing app' guide

[davidfowl]

Summary

The Aspireify an existing app guide (src/frontend/src/content/docs/get-started/add-aspire-existing-app.mdx) is framed as a polyglot guide, but the end-to-end walkthrough and many concrete examples are still heavily C#-centric.

Why this needs follow-up

The page already uses a language selector and introduces C#, Python, and JavaScript as supported paths, so readers reasonably expect the walkthrough to stay language-aware throughout. Right now, the page still leans on .NET solution/project language and mostly C# examples, which makes the Python and JavaScript paths feel incomplete.

Follow-up work

• Audit the guide section by section for C#-specific assumptions.
• Decide whether the page should become truly polyglot throughout, or explicitly scope some sections to C#.
• Add Python/JavaScript parity where the product supports it.
• Replace .NET-centric wording in shared prose when the guidance applies across languages.

Context

This came up during the broader docs pass that:

• moved .NET docs under Integrations -> Frameworks & runtimes -> .NET
• expanded Project resources
• audited .NET-centric wording in the JavaScript starter quickstart