feat: qualify native Claude function image results

[SaladDay]

Claude previously rejected every public function image result. This adds successful inline PNG/JPEG results for environment:none, preserving ordered caller content while accepting native image resizing. Failed images, workspace images and remote references remain rejected before batch persistence. Core reuses the common result contract and checks Runtime image support only for image-bearing delivery.

Native receipt validation retains Session/call ownership, success, text, block order/count and image presence. Coverage documents the distinct Codex transport acknowledgement limitation without changing its lifecycle.

Validation:

• Real Kimi API through independent Core, PostgreSQL and Docker Runtime for Codex and Claude: fixed SDK/raw HTTP, PNG/large PNG/JPEG, failed text, retries/conflicts, cancellation, cold continuation and tenant isolation.
• All make check components passed (server Core/runtime/database gates and local Core Web gate, including 73 Playwright cases); packaging expectation corrected and failed/remaining gates rerun.
• Targeted Go race tests, generated OpenAPI and fresh independent GPT-6 Astra high review passed.

This qualifies the documented subset, not complete protocol compatibility.

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