fix: align startup banner URL defaults with actual service defaults

[chinaux]

Summary

The startup banner in reme/utils/logo_utils.py was using hard-coded defaults (localhost, 8000) when rendering the service URL for http and mcp (non-stdio) backends. These defaults did not match the actual service defaults defined in reme/constants.py (REME_DEFAULT_HOST, REME_DEFAULT_PORT), so the banner could display a misleading URL when the user relied on the default configuration.

This PR aligns the banner URL defaults with the real service defaults by importing REME_DEFAULT_HOST and REME_DEFAULT_PORT from reme.constants.

Changes

• reme/utils/logo_utils.py:
  • Import REME_DEFAULT_HOST and REME_DEFAULT_PORT.
  • Use them as fallbacks for host and port in both http and mcp (non-stdio) branches.

Motivation

When starting the ReMe HTTP service without explicitly setting host/port, the banner previously showed http://localhost:8000 even though the actual listening address might default to a different host/port (as defined in reme.constants). This can confuse users who copy the URL from the banner.

[jinliyl]

Thank you for identifying and addressing this issue! The underlying problem was valid, but it has since been resolved more comprehensively in #453, which uses the instantiated service values for the resolved host, port, and MCP transport, and also adds test coverage. Since #453 has already been merged, this PR is now superseded. Thanks again for the contribution!