feat(analysis): preserve dynamic multi-agent workflows

[drewstone]

Summary

• preserve resumed Claude Workflow runs, parallel child ordering, missing-parent evidence, and task-scoped selection
• discover external subagent transcripts safely and include every parsed source in trace identity
• harden external analysts, cancellation, span ordering, and Codex child-session parsing
• add dynamic workflow investigation through agent-eval 0.137.0 with concise validated examples

Why

Trace analysis previously lost or misassigned workers when sessions resumed, Workflow stored children under another session, or automated prompts started a task. That made task-scoped analysis incomplete and could attach work to the wrong parent.

Proof

• pnpm test: 368/368 passed across 32 files
• pnpm typecheck, pnpm build, pnpm check:package: passed
• pnpm audit --prod: 0 known production vulnerabilities
• real Claude corpus: 48/51 parseable Workflow roots passed; the other 3 are pre-existing conflicting-event sources; 552,567 spans checked with 0 missing parent references, 0 bad step sequences, and 0 parent-after-child ordering errors
• external Workflow case: 38/38 child transcripts discovered and assigned to the correct parent
• active Codex case: 27 connected sessions, 6,780 spans, and 0 relationship errors

One dangling Workflow directory has no parent transcript and is excluded from the 51-root parse set.