🎨 Palette: Add skip to main content link

[ELO2026X]

💡 What: Added a "Skip to main content" link at the top of the application and updated the ContentView wrapper to act as the main content area with an ID of #main-content.
🎯 Why: To allow keyboard-only and screen reader users to easily bypass the sidebar and jump straight to the main visual effects explorer area.
📸 Before/After: No visual change for mouse users, a "Skip to main content" button will pop up in the top left when a user focuses on the window using Tab.
♿ Accessibility: Significant improvement for keyboard navigation and screen reader users, allowing them to bypass the sidebar on initial page load.

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PR created automatically by Jules for task 15002763852002453164 started by @ELO2026X

[google-labs-jules]

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