fix(mcp): unpin GoodMemory install

[hjqcan]

Summary

• remove the GoodMemory version pin from the structured installCommand
• remove the same pin from the installation example

Why

This follows the maintainer suggestion on #5774. npm install -g goodmemory resolves npm latest, so the directory entry does not become stale after every GoodMemory release. As of this PR, npm latest is 0.7.4.

The separate MCP Registry metadata drift is confirmed: its versions/latest endpoint still returns 0.5.1. A v0.7.4 manifest passes mcp-publisher validate, but republishing is currently blocked on refreshing the expired registry authentication token; this PR does not claim that registry issue is resolved.

Validation

• pnpm validate:content:strict — passed for 1,388 content files; 24 existing warnings are outside this entry
• git diff --check

Refs #5774.

[hjqcan]

Registry follow-up is now complete. The official MCP Registry accepted io.github.hjqcan/goodmemory version 0.7.4 from the immutable GoodMemory v0.7.4 manifest. A fresh read now reports:

registry server version:  0.7.4
registry package version: 0.7.4
npm latest:               0.7.4
updatedAt:                2026-08-17T02:11:27.921374Z

Registry endpoint: https://registry.modelcontextprotocol.io/v0.1/servers/io.github.hjqcan%2Fgoodmemory/versions/latest

This resolves the stale retrieval source noted on #5774; this PR resolves the separate recurring install-pin drift. All required checks on this PR are green.