docs: clarify authority runner execution provenance boundary

[dinakarjs]

The merged authority-comparison runner accepts independent_live_reproduction=true when basis is independent_run, but validate_report does not authenticate the producer or verify execution provenance. Clarify this boundary in the README and comparison-contract.json so consumers do not treat validator acceptance as independent execution evidence.

Addresses the documentation follow-up reiterated in Carlos's #288 approval: #288 (review). Based on merged main 5f9b48e.

README and contract explanatory text only; contract keys, schema and runtime behavior are unchanged. Existing adapters retain author_record and independent_live_reproduction=false. Any provenance-appraisal layer remains separately reviewed future work.

Also regenerate marketplace/catalog.json: #288's merged catalog has count 46 while its list contains 47 integrations. The generator changes only count to 47; no metadata or tier changes.

Validation: JSON and diff checks pass; five Marketplace generator tests pass and generator --check is current. Existing focused validator/reference/boundary controls ran 14 tests (13 passed, one TRACE-dependency skip in the reused local environment). A process-only control confirmed that an independent_run/true assertion is accepted without provenance artifacts while author_record/true is refused.

Hosted authority-evidence checks, lint, links and other functional workflows passed at the initial head. Validate integrations identified the stale catalog, now corrected at b0a1072; hosted checks are rerunning. Initial local full-fixture attempt lacked downloaded vendor fixtures and was not green; no fresh native execution claim. Maintainer approval is still required.

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[dinakarjs]

CI follow-up at b0a1072: the authority evidence check, lint, documentation and other functional workflows passed on the initial head; Validate integrations found an existing stale Marketplace count after #288 merged. Running the repository generator changes only count: 46 -> 47. Added that generated correction; generator --check and all five catalog tests pass locally. No integration metadata or tier changed. CI will rerun on this head; maintainer approval remains required.

[imran-siddique]

Reviewed b0a1072. The README and contract now make clear that independent_live_reproduction is a producer-supplied assertion and that validator acceptance does not establish independent execution. The catalog count matches its 47 entries. All 12 returned CI workflows pass. This resolves the documentation follow-up from #288.