fix: validate MCP registry metadata

[aryamthecodebreaker]

What changed

• Shorten the MCP server description from 109 to 96 characters to satisfy the Registry's 100-character limit.
• Add check:server-manifest to normal repository CI so server name, version, npm mapping, and description constraints are checked on every PR.
• Add the same description validation to the release preflight before any npm publication.
• Bump the coordinated release metadata and Action example to 0.6.1.

Root cause

The v0.6.0 trusted-publishing run successfully published both npm packages, then the MCP Registry rejected server.json with HTTP 422 because description exceeded 100 characters. Since npm versions are immutable, this patch uses a transparent 0.6.1 recovery release rather than moving or rewriting the v0.6.0 tag.

Validation

• npm run ci — green, including the new server-manifest check (96/100 characters), 119 tests, typecheck, lint, production build, Action checks, smokes, evaluation, and benchmark
• node scripts/evaluate-external.mjs --gate --check-recorded — unchanged at 50% top-1, 83.3% top-3, 83.3% top-5
• npm pack dry-runs — correct CLI/core 0.6.1 artifacts
• git diff --check — clean