feat: implement interactive .NET version selection

[BirajMainali]

Motivation: Installing the latest version isn't always appropriate (compatibility, LTS, legacy projects). This change lets users pick the exact stable minor/patch they need rather than forcing latest.

What I changed:

• Behavior: Show interactive list of stable .NET versions and install the chosen one.
• Filtering: Exclude rc and preview releases.
• Deduplication: Keep one entry per minor version (latest patch).

Artifacts

[AndrewMast]

Might be interesting to add --latest flag to skip the prompt, not sure if that's scope creep though. Maybe even --version=[version] would be nice.

[BirajMainali]

Might be interesting to add --latest flag to skip the prompt, not sure if that's scope creep though. Maybe even --version=[version] would be nice.

I’ve condensed the current environment setup/installation flow as Install > Development > *. I’m not sure how we might handle adopting explicit versions in the TUI. Personally, I like this flow; I took inspiration from the Remove > web app > * sequence.