fix: correct Litestar MCP registry metadata

[cofin]

Summary

• correct the Litestar MCP website and documentation links
• align its description and Litestar compatibility floor with published package metadata
• fix the malformed maintainer avatar URL
• add and select the upstream Litestar MCP project icon
• refresh generated metadata through the registry's targeted sync path

Root cause

The existing registry record contains copied placeholder metadata: its documentation link points to Advanced Alchemy, its avatar URL contains a duplicated scheme, and its compatibility floor predates the current package requirement.

User impact

The Litestar plugins site will direct users to the correct MCP documentation, display accurate compatibility information, and use the project's own icon.

Validation

• targeted sync("litestar-mcp") metadata refresh
• registry schema decode for the corrected YAML entry
• SVG XML parse for the upstream icon
• documentation URL returned HTTP 200
• git diff --check

The repository's existing uv run pytest baseline still fails because parse_requires_python() no longer enumerates Python 3.7 and 3.8 while its test expects them. The existing uv run ruff check . baseline also reports the pre-existing unused json import in src/main.py; neither failure is touched by this metadata-only change.