feat(ui): integrate PagerDuty page and update entity page components

[tfhartmann]

Small updates to make the homepage and entitity pages a bit more readable.

[Copilot]

Pull request overview

Updates the Backstage app UI to improve homepage/entity-page readability while adding PagerDuty navigation and entity-level PagerDuty visibility.

Changes:

• Reordered and regrouped homepage cards, adding a “Getting Started Documentation” InfoCard and moving “Top/Recently Visited” sections.
• Updated the entity overview to use the PagerDuty “small” card variant and adjusted card placement; reordered the Docs tab route.
• Added a top-level /pagerduty route for the PagerDuty plugin and reformatted sidebar items.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

File	Description
backstage/packages/app/src/components/Root/Root.tsx	Reformats sidebar items for consistency/readability.
backstage/packages/app/src/components/home/HomePage.tsx	Reorganizes homepage layout and adds getting-started documentation links.
backstage/packages/app/src/components/catalog/EntityPage.tsx	Switches to PagerDuty small card and adjusts overview/docs route placement.
backstage/packages/app/src/App.tsx	Adds a /pagerduty route rendering the PagerDuty plugin page.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[gemini-code-assist]

Code Review

This pull request integrates PagerDuty by adding a dedicated route and a small card to the entity overview, reorders the home page layout to prioritize documentation, and adjusts the entity page layout. Feedback suggests optimizing the grid structure in the entity page, using the Link component for internal navigation on the home page to maintain SPA behavior, and adding the new PagerDuty route to the sidebar for better visibility.