Add v1.5 announcement banner to v1 project page

[Copilot]

Adds prominent banner on v1 project page directing users to the new v1.5 release to drive traffic.

Changes

• Banner placement: Positioned immediately below page title for maximum visibility
• Styling: Purple gradient (#667eea → #764ba2) with hover effects, matches existing site aesthetic
• Implementation: CSS classes in existing <style> block, proper semantic HTML with ARIA attributes
• Link: Opens v1.5 page (https://ace-step.github.io/ace-step-v1.5.github.io/) in new tab

Visual

The banner displays: "🎵 NEW: ACE-Step v1.5 is Now Available! 🚀" with a white CTA button below.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• ace-step.github.io
  • Triggering command: /usr/bin/curl curl -I REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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