Replace auction banner with domain migration notice

[Copilot]

This PR replaces the banner text that currently links to the auction draft page with a migration notice informing users about the upcoming domain change.

Changes Made

Before: The banner displayed "Quantex 2025 Auction Draft" as a clickable link to /auction

After: The banner now displays "This page will be moved to https://arcaneire.github.io/ilol-ladder after October 6, 2025 due to domain expiry."

Technical Details

• Replaced the <a href="/auction"> element with a <span> element to remove link functionality
• Updated the corresponding CSS selector from .auction-banner a to .auction-banner span
• Preserved all existing styling and the close button functionality
• Maintained UTF-16 encoding compatibility for the build process

Testing

• ✅ Banner displays the migration notice correctly
• ✅ Close button still works to hide the banner
• ✅ Styling remains consistent with the existing design
• ✅ No impact on the Python build process or other functionality

The migration notice ensures users are informed well in advance of the domain change while maintaining the same visual appearance and user experience.

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