chore: formalize v0.7.0 release after benchmark-contract merge

[sauravsingla]

Goal

Publish the first formal GitHub release after documentation consistency and benchmark-contract work is merged.

Preconditions

• Issue bench: define publication-grade controlled-hardware campaign #9 contract merged
• main CI green
• CHANGELOG updated
• version metadata checked for consistency
• release notes clearly distinguish implemented capability, hosted-CI engineering evidence, and future publication-grade work

Target

v0.7.0