test(codegen): lock @deprecated JSDoc generation on deprecated JSON Schema properties

[bokelley]

Closes #1915

Summary

Extends test/jsdoc-constraints-codegen.test.js with a new describe block that locks the contract between deprecated: true in JSON Schema and @deprecated JSDoc in generated TypeScript. Filed in response to the expert review on adcontextprotocol/adcp#4904, which flagged that deprecated: true propagation through json-schema-to-typescript is partially reliable across toolchain versions.

Three regression tests added:

• emits @deprecated JSDoc on a property with deprecated: true — mirrors the AdCP 3.1 additive-deprecate pattern (CreateMediaBuySuccess.status / UpdateMediaBuySuccess.status), asserts both the tag and the deprecation description text survive
• does not emit @deprecated on a sibling property without deprecated: true — confirms the tag is property-scoped, not type-level
• preserves description text alongside @deprecated when both are present — also asserts @minimum from injectJsdocConstraints survives alongside @deprecated (the coexistence case)

All tests use synthetic fixture schemas via runCodegenPipeline() — hermetic, no dependency on schemas/cache/latest/ or dist/.

No changeset needed (test-only change per CLAUDE.md).

What was tested

• NODE_ENV=test node --test test/jsdoc-constraints-codegen.test.js — 10 pass, 6 skip (dist not built — expected), 0 fail
• All 3 new tests in the @deprecated JSDoc — codegen regression lock suite pass
• All 7 existing tests in injectJsdocConstraints — synthetic end-to-end continue to pass

Pre-PR review

• code-reviewer: approved — no blockers; 2 nits (global /@deprecated/ regex is safe given jsts property-scoping; test 2 uses a separate schema compile rather than asserting doesNotMatch on the sibling within test 1's schema — correct isolation)
• ad-tech-protocol-expert: approved — non-breaking per spec; asserting on ts output (not zod) is the correct lock; nit that adcp#4904 reference in the comment could become stale if that PR is retracted (not a behavior concern)

Nits noted (not fixed): both nits are style-level. The /@deprecated/ global scan is safe because jsts v15 places the tag only on the property JSDoc block, confirmed in generator.js:269. The adcp#4904 citation is also cited in the issue body and in the existing core.generated.ts deprecation context; stale risk is low.

Triage-managed PR. This bot does not currently iterate on
review comments or PR conversation threads (only on the source
issue). To unblock:

• Push fixup commits directly: gh pr checkout <num> →
  fix → push.
• Or re-trigger: comment /triage execute on the source
  issue.

See adcp#3121
for context.

Session: https://claude.ai/code/session_018C9sUVC7R2zmTneFAH8PEp

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