Add CI/CD: consistency validator, link check, tag-based releases

[bfish1996]

What

• scripts/validate.py — enforces the contracts the docs already declare: parses ontology.yaml / plugin.json / evals.json / config template / all SKILL.md frontmatter; frontmatter name must match its directory; plugin.json must list exactly the skills/ dirs; every ontology entity, property, relation, and fixed enum value must be covered by registry-schema.md and mapped (canonical:) in each connectors/*-schema.md guide.
• .github/workflows/ci.yml — runs the validator + lychee offline link check on PRs and main. A third advisory job (PR-only, never blocking) sends changed schema docs to Ollama Cloud to flag semantic drift the mechanical check can't see; it skips silently unless the OLLAMA_API_KEY secret is set.
• .github/workflows/release.yml — on a v* tag: verifies the tag matches plugin.json version, re-runs the validator, and publishes a GitHub Release whose body is the matching CHANGELOG.md section (fails if missing) plus auto-generated notes.
• CHANGELOG.md seeded with v0.1.0; README gets a CI badge and the release convention.

Verified

• validate.py passes on clean main and fails with a named violation for each broken invariant (skill removed from manifest, unmapped property in a connector guide, mismatched frontmatter name, enum value missing from prose).
• Changelog extraction and tag↔version logic tested locally, including the missing-section failure path.
• All relative markdown links resolve (one template file with [<source>](<url>) placeholders is excluded from lychee).

🤖 Generated with Claude Code