M8f — v1.1: progress + result_chunk

[nficano]

Goal

v1.1: progress + result_chunk.

Scope

• Add progress body schema (§8.2.1) and JobContext.progress
• Add result_chunk body schema (§8.4); JobContext.stream_result async-context-manager writer; JobHandle.chunks() async iterator + JobHandle.collect_chunks()
• Enforce "no mix inline+chunked" in Job.emit_result
• Add §14 chunk-size cap with INTERNAL_ERROR
• Examples: progress/, result_chunk/

Spec §

§8.2.1, §8.4, §14

Risk

M (R5 result_chunk size cap)