fix: update Traefik middleware when basic auth credentials change

[xiaxia-unlimited]

Summary

When updating basic auth username or password, the Traefik middleware configuration was not being updated.

This fix:

1. Gets the original record before update
2. If username or password changed, removes old middleware
3. Creates new middleware with updated credentials

Fixes #3749

Testing

1. Create an application with basic auth
2. Update the basic auth password
3. Verify the Traefik middleware is updated with new credentials

Greptile Summary

This PR fixes a bug where Traefik middleware was not being updated when basic auth credentials were changed. The fix retrieves the original record before update, then removes the old middleware and creates new middleware with updated credentials when username or password changes.

Confidence Score: 4/5

• This PR is safe to merge with minor inefficiency noted
• The logic correctly handles credential updates by removing old middleware and creating new one. The implementation is straightforward and addresses the reported issue. Score is 4 instead of 5 because the code unnecessarily updates middleware even when credentials haven't actually changed (user provides same values), though this is a minor inefficiency rather than a bug.
• No files require special attention

_{Last reviewed commit: ca0dc01}

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[greptile-apps]

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[greptile-apps]

unnecessary middleware update when credentials unchanged - if user provides same username and password values, middleware will be removed and recreated unnecessarily