Unify request attribution and isolate background operations

[fengjikui]

Summary

• introduce a shared actor/relation/operation attribution contract for main turns, subagents, harness operations, and independent Codex background jobs
• extract only allowlisted request-header semantics before redaction and keep private identifiers out of attribution evidence
• render independent background jobs as standalone timeline nodes outside Turn numbering, Turn Rail, latest-turn selection, and conversation statistics
• expose attribution confidence and evidence in request metadata, with bilingual copy and updated architecture contracts

Evidence

• classified the real Codex memory-extraction request #38 as an independent background service operation
• preserved compaction as a current-dialogue harness operation and subagent traffic as child-dialogue work
• verified the standalone background node in the live Viewer and retained full detail access

Validation

• npm run release:check:macos (passed in 486.1s)
• focused request-profile, proxy, timeline, Viewer, i18n, package, and suggestion-mode contracts
• git diff --check