CmdPal: Extension Gallery - Allow only HTTP/HTTPS URIs as links in the UI

[jiripolasek]

Summary of the Pull Request

This PR filters URIs from extension gallery and allows only HTTP/HTTPS URIs as links for the installation page.

PR Checklist

• Closes: #xxx

• Communication: I've discussed this with core contributors already. If the work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end-user-facing strings can be localized
• Dev docs: Added/updated
• New binaries: Added on the required places
  • JSON for signing for new binaries
  • WXS for installer for new binaries and localization folder
  • YML for CI pipeline for new test projects
  • YML for signed pipeline
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[Copilot]

Pull request overview

This PR tightens CmdPal extension gallery link handling by filtering gallery and WinGet metadata links so only HTTP/HTTPS URIs are exposed as clickable UI links.

Changes:

• Adds cached web-only URI fields for homepage, author page, and install link commands.
• Filters source and metadata detail links through HTTP/HTTPS validation.
• Adds unit tests covering non-web gallery links and WinGet metadata links.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Gallery/ExtensionGalleryItemViewModel.cs	Restricts gallery links and source detail links to HTTP/HTTPS before exposing commands or hyperlink URIs.
src/modules/cmdpal/Tests/Microsoft.CmdPal.UI.ViewModels.UnitTests/ExtensionGalleryItemViewModelTests.cs	Adds tests verifying non-web gallery and WinGet metadata links are ignored while safe web links remain available.