Finalize v1.1.0 release blockers: manifest, receipts, examples, spec, docs, checksums

[GsCommand]

Motivation

• Finalize the v1.1.0 release-candidate by removing ambiguous draft wording, resolving schema correctness blockers, and aligning prose to the repository-validated pre-publication posture.
• Ensure receipt contracts and examples are symmetric and correct (merchant present on authorize receipts; reason required only for failed outcomes where applicable) so conformance tooling and downstream integrators have an unambiguous surface.

Description

• Set manifest.json status to a single definitive value current and updated validation to enforce that posture by changing the manifest assertion in scripts/validate-all.mjs.
• Require merchant in schemas/v1.1.0/commercial/authorize/authorize.receipt.schema.json to restore actor symmetry with request contracts.
• Adjust schemas/v1.1.0/commercial/checkout/checkout.receipt.schema.json and schemas/v1.1.0/commercial/purchase/purchase.receipt.schema.json so reason is required for failed only and no longer required for pending.
• Make the verify invalid fixture examples/v1.1.0/commercial/verify/invalid/900-verify.receipt.invalid.json explicitly and intentionally invalid (updated receipt_id and basis) so the invalid set contains only true negatives.
• Add payment_input to the commercial payment grammar in SPEC.md so the spec matches the current schema surface.
• Expand CHANGELOG.md and finalize releases/v1.1.0.md with concrete Added/Changed/Removed notes, and remove unfinished draft language from SECURITY_PROVENANCE.md while still accurately stating the repository-validated, not-yet-published posture.
• Regenerated checksums.txt to reflect the updated artifacts.
• Committed the changes under a single commit (Finalize v1.1.0 release blockers).

Testing

• Ran npm install which completed successfully.
• Regenerated integrity ledger with npm run generate:checksums which wrote updated checksums.txt successfully.
• Validated the intentionally-invalid verify fixture against the verify receipt schema using an Ajv2020 check, which correctly reported the fixture as invalid.
• Ran full validation with npm run validate (which runs validate:schemas, validate:examples, validate:integrity, and validate:pack) and the suite completed successfully after the fixes.

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Codex Task