Split Dreaming readback artifact helpers

[yvette-carlisle]

Summary:

• Split service-native Dreaming readback artifact helpers into dreaming_readback_artifacts.rs.
• Kept dreaming_readback.rs focused on adapter entrypoints, suite materialization selection, async ElfService::list readback, and orchestration.
• Added focused unit coverage for template selection, scoring evidence/trap filtering, artifact stamping/source refs, content flattening, and trace-stage output.

Validation:

• cargo make fmt-rust
• cargo check -p elf-eval --bin real_world_live_adapter --all-features
• cargo nextest run -p elf-eval --bin real_world_live_adapter --all-features dreaming_readback_artifacts (4 passed)
• cargo nextest run -p elf-eval --test real_world_job_benchmark --all-features service_native_dreaming_readback_report_materializes_public_jobs (1 passed)
• cargo make fmt-rust-check
• git diff --check
• cargo make check-rust
• cargo make lint-vstyle
• cargo make lint-rust
• cargo make test-rust (394 passed, 92 skipped)
• cargo make check (394 passed, 92 skipped)

Review:

• Scout selected the service-native Dreaming artifact helper split as the next safest production/bin modularization slice.
• Skeptic passed with no blockers or material risks.