Fix Store publish input and refresh screenshots

[Xueyang-Song]

Summary

• Fix the Store release workflow for the current msstore publish CLI by using --inputDirectory instead of the removed --inputFile option.
• Refresh website screenshots and cache-bust the landing page screenshot URLs so the deployed site picks up the new light/dark captures.
• Add public-preview launch/automation plumbing so screenshot automation can open Home and repo pages without a user GitHub token.

Root cause

The retry of Publish JitHub to Microsoft Store on main got past the old WinUI migration gate, built the x64/ARM64 .msixupload, then failed because msstore publish rejected --inputFile. The CLI help emitted in the failing run now documents --inputDirectory for the folder containing .msix / .msixupload packages.

Failing run: https://github.com/JitHubApp/JitHubV2/actions/runs/25327763503

Validation

• git diff --check
• dotnet build .\JitHub.slnx -c Debug -p:Platform=x64
• Confirmed the old WinUI Store release blocker text/input is gone from .github, docs, and README.

Notes

msstore is not available on this local PATH, so the CLI-specific validation is based on the failed GitHub Actions run's own msstore publish --help output.