Relax ScaffoldHub dependency constraint to >=0.1.6

[Timandes]

Summary

Update the ROCK MCP extra to depend on scaffoldhub>=0.1.6 instead of pinning exactly 0.1.6.

Scope

• Relax the dependency constraint in pyproject.toml.
• Regenerate/update uv.lock consistently.
• Update the packaging assertion and relevant dependency documentation.

Rationale

Allow compatible ScaffoldHub releases newer than 0.1.6 while retaining 0.1.6 as the minimum supported version.