[Feature] Add a Flameox-compatible profiler receipt interoperability fixture

[morluto]

Motivation

GitContribute now has a versioned external validation receipt boundary through validation.attach_receipt, and its evidence model can retain producer, source revision, artifact digests, command, environment, limitations, and run identity. What is missing is a producer-neutral interoperability fixture proving that a Flameox-style profiler result survives attachment, storage, retrieval, and evidence summarization without being flattened into prose.

This is not a request to add a new profiler or to execute a profiler implicitly. It is a compatibility and validation task for the existing receipt boundary. Flameox already has versioned artifact and provenance machinery; the two projects need one stable sample contract.

Proposed outcome

Add a bounded, checked-in receipt fixture representing an external profiler run and test that GitContribute:

• validates its version and required provenance;
• preserves source/revision and artifact identity;
• retains command, environment, provider/run identity, and limitations;
• distinguishes complete, incomplete, and invalid evidence; and
• exposes the receipt through the existing evidence/resource handoff.

The fixture should use public, producer-neutral fields or document an adapter mapping rather than coupling GitContribute to Flameox internals.

Acceptance criteria

• A stable Flameox-compatible fixture is accepted by validation.attach_receipt.
• Digest, source identity, run identity, artifact, and limitation fields round-trip unchanged.
• Invalid or incomplete receipts fail or remain explicitly qualified.
• No command execution, network access, or profiler dependency is introduced.
• The fixture and test are documented as an interoperability contract.