maintenance: refresh Unified AI System snapshot to v0.4.9

[happy520ai]

Maintenance update

The existing Unified AI System plugin snapshot still referenced v0.4.8 in its MCP Registry URL, Docker commands, release link, and version notes.

This PR updates the already-listed snapshot to the published v0.4.9 release:

• ai-gateway-service:0.4.9
• mcp-server:0.4.9
• Official MCP Registry 0.4.9 URL
• Release and visible version references

The update changes only the existing plugin snapshot. It does not change the marketplace schema or add production, L5, or AGI claims. The provider-free demo remains the default documented proof path.

Validation:

• release v0.4.9 is published, non-draft, and non-prerelease
• Official MCP Registry 0.4.9 endpoint returns HTTP 200
• all stale 0.4.8 references are absent from the updated snapshot
• git diff --check passes

Source evidence:

• Release: https://github.com/happy520ai/unified-ai-system/releases/tag/v0.4.9
• Official MCP Registry: https://registry.modelcontextprotocol.io/v0.1/servers/io.github.happy520ai%2Funified-ai-system/versions/0.4.9
• Current source: https://github.com/happy520ai/unified-ai-system

[happy520ai]

Thanks for reviewing. This PR only refreshes the marketplace snapshot to the current public release, v0.4.7. The first-run path is provider-free and requires no API key: docker run --rm ghcr.io/happy520ai/unified-ai-system/ai-gateway-service:0.4.7 pnpm gateway demo Build-a-small-API-for-my-team --enhance --profile coding. The change keeps the entry aligned with the published README and release metadata.