Add support for `*.localhost` domains

[CharlieDigital]

Which client?

Web

The problem

The v2.x inspector currently only accepts a select set of literal hosts when using http; all others require https.

However, *.localhost is a reserved TLD for local domains per:

• https://www.rfc-editor.org/info/rfc6761/
• https://www.rfc-editor.org/info/rfc2606/

   To safely satisfy these needs, four domain names are reserved as
   listed and described below.

                   .test
                .example
                .invalid
              .localhost

      ".test" is recommended for use in testing of current or new DNS
      related code.

      ".example" is recommended for use in documentation or as examples.

      ".invalid" is intended for use in online construction of domain
      names that are sure to be invalid and which it is obvious at a
      glance are invalid.

      The ".localhost" TLD has traditionally been statically defined in
      host DNS implementations as having an A record pointing to the
      loop back IP address and is reserved for such use.  Any other use
      would conflict with widely deployed code which assumes this use.

Context: local dev runtime uses a proxy on a *.localhost domain that routes to the inspector.

Solution you have in mind (optional)

Allow *.localhost domains over http

Alternatives or workarounds you have tried

Use direct address

Already built it locally?

No response

Before you submit

• I searched existing issues and this is not a duplicate.
• This is a request for the Inspector itself, not for the MCP specification or an SDK.