Release v2.5.0: reviewed drug vocabulary and guarded course linkage

[NickLeko]

Packages exp-003 (db49231) as v2.5.0: listed generic/brand drugs can replace a qualifying therapy class only within the guarded course-sentence grammar. An unresolved eligible drug mention alongside another course requires review. The PR includes the experiment's rejected-candidate evidence and accepted linkage revision.

Documents engine/data/cpb0236_drugs_v1.json as owner-approved reviewed data and requires human verification of ATC codes against WHO ATC before any external claim. Release notes preserve the owner's held-out statement verbatim, including the leading-verb limitation. Held-out cases were not inspected or rerun during release preparation.

Release prep changes no extraction logic or table bytes relative to db49231. It updates engine/app version and two hardcoded assertions, adds 16 executable contract examples while preserving all 51 earlier examples and four known-failure objects, and reconciles current docs/counts. Record schema remains 2.0.0.

Validation:

• make test: 1301 passed, 10 existing xfailed.
• make lint: green.
• Corpus: 52/52; exp-003: 74/74; exp-002: 64/69, all identical to exp-003's final reports. Zero false PENDING_VERIFICATION on these final tested sets.
• Fixed acceptance clock 2026-09-01T00:00:00Z: all 25 generator writes audited; 12 version-only changes, 13 byte-identical outputs.
• Governance preflight and independent output hashes confirm no governance or non-version changes; restore-and-stop condition did not trigger.
• docs/releases/v2.5.0-doc-audit.md and v2.5.0-scope-audit.json record documentation drift and scope checks.

No merge, tag, policy-monitor write, runtime-clock change or deployment verification is included.