docs: document Planr 1.7 CLI-first evaluations

[regenrek]

Why:

• add the missing Planr 1.7.0 entry to the README release summary
• make clear that the full evaluation workflow works through the CLI and MCP is optional

How:

• link the eval contract, CLI reference, and 1.7.0 changelog
• record the CLI-first clarification under Unreleased

Tests:

• pnpm docs:verify-release
• 59 routes, 146 internal links, 38 redirects; no unfinished markers or duplicate anchors