Use handle_metadata for web url

[thomasjpfan]

Describe your changes

Fixes https://linear.app/modal-labs/issue/SDK-612/gpu-fallback-functions-arent-identified-as-web-endpoints-on-deploy

Checklists

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Compatibility checklist

Check these boxes or delete any item (or this section) if not relevant for this PR.

• Client+Server: this change is compatible with old servers
• Client forward compatibility: this change ensures client can accept data intended for later versions of itself

Note on protobuf: protobuf message changes in one place may have impact to
multiple entities (client, server, worker, database). See points above.

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Release checklist

If you intend for this commit to trigger a full release to PyPI, please ensure that the following steps have been taken:

• Version file (modal_version/__init__.py) has been updated with the next logical version
• Changelog has been cleaned up and given an appropriate subhead

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[!NOTE]
Use web URL from handle metadata when reporting function creation and add a test to verify it’s displayed.

• Function creation status:
  • Use response.handle_metadata.web_url when displaying created web function URL; continue printing warnings, proxy auth suffix, suffix from web_url_info, and custom domains.
• Tests:
  • Add test_url_displayed_function_create_status_web_url to verify the web URL from handle metadata is printed in the finish message.

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[freider]

Lets add some tests for this too (I had claude do that earlier today but they weren't very good)

[thomasjpfan]

I added a unit test for FunctionCreationStatus specifically for web_url.

[thomasjpfan]

@prbot approve

[modal-pr-review-automation]

Please request a reviewer to follow up with a post-merge review.

[mwaskom]

Thanks!