Update favicon to Dev Proxy icon

[Copilot]

Replace default Astro favicon with the official Dev Proxy icon from dotnet/dev-proxy/media.

• public/favicon.svg → Dev Proxy SVG icon
• public/favicon.ico → Dev Proxy ICO (16×16, 32×32)

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:

• telemetry.astro.build
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node node /home/REDACTED/work/dev-proxy-tools.github.io/dev-proxy-tools.github.io/node_modules/.bin/astro build (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)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Update favicon</issue_title>
<issue_description></issue_description>

<agent_instructions>Get icon from https://github.com/dotnet/dev-proxy/tree/main/media</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Update favicon #7

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