ci(docs): enforce governed knowledge records

[testikun]

Problem

Issue #198 established the forward-only knowledge and evidence contract, but new Research and Benchmark records still have no repository check for required metadata, category-index reachability, or local link integrity. A complete-looking Benchmark can therefore omit frozen identities, accounting, failure classification, limitations, or a retrievable evidence reference without failing CI.

Value

• Makes future governed Research and Benchmark records reviewable from a clean checkout.
• Keeps legacy documents untouched until an explicit migration.
• Fails visibly on structural evidence gaps without claiming that a well-formed record is independently validated.

Approach

• Add a dependency-free check-knowledge-contract.mjs for governed records under docs/research and docs/benchmarks.
• Treat frontmatter as the explicit opt-in boundary; records without it remain legacy.
• Require shared lifecycle/provenance metadata, Research fact/inference/recommendation/unknown sections, and Benchmark source/model/task/verifier/accounting/failure/limitations/evidence/rerun fields.
• Verify every governed record is linked from its category index and that repository-relative Markdown links resolve inside the checkout.
• Add Research and Benchmark templates, wire the check into bun run check, and append the Decision-0001-backed promise to the discipline ledger.
• Keep this complementary to ci: validate decision document metadata #309, whose open PR validates Decision-only metadata.

Validation

• bun run check — passed.
• bun run test — passed: 1246 Node tests passed, 1 platform test skipped; 30/30 Vitest tests passed.
• Focused knowledge-contract tests — 5/5 passed, covering valid records, legacy exclusion, missing Benchmark evidence fields, unindexed records, and broken links.
• git diff --check — passed.

Impact

• User-visible behavior: none.
• Model-visible context/tools: none.
• Runtime/lifecycle: none; CI/documentation validation only.
• Persisted config/data: none.
• Compatibility/risk: low. Existing records without frontmatter are intentionally ignored, and no ignored/local evidence is scanned or published.

Refs #198.