Float the GitHub link outside navigation

[ShoGinn]

Summary

• move the GitHub repository link out of the app navigation
• render it as an accessible floating GitHub icon in the bottom-right corner
• replace the plain Railway URL with a clickable Railway live badge
• update the app shell test for the icon link label

Verification

• visually checked desktop and mobile layouts
• frontend tests
• frontend typecheck
• frontend lint and formatting
• pre-commit and pre-push hooks

[railway-app]

🚅 Deployed to the tax-tracker-pr-86 environment in endearing-eagerness

Service	Status	Web	Updated (UTC)
tax-tracker	✅ Success (View Logs)	Web	Aug 2, 2026 at 12:18 am

[Copilot]

Pull request overview

This PR updates the frontend shell and project README to make the GitHub repository link less intrusive by moving it out of the primary navigation and rendering it as a fixed-position floating action button, while also improving the Railway deployment link presentation in the README.

Changes:

• Replace the sidebar GitHub nav item with a bottom-right floating GitHub icon link (with accessible labeling).
• Add styling for the floating GitHub button, including safe-area inset handling for mobile.
• Replace the README’s plain Railway link with a clickable Railway “live” badge and update the AppShell test accordingly.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
README.md	Replaces the plain Railway URL section with a clickable “Railway live” badge.
frontend/src/index.css	Adds .github-fab styles to render the GitHub link as a floating bottom-right button.
frontend/src/app/AppShell.tsx	Removes the GitHub link from the sidebar nav and adds a floating, accessible GitHub icon link.
frontend/src/app/AppShell.test.tsx	Updates the expected accessible name for the GitHub link to match the new FAB aria-label.