feat(agents): Draw the run canvas as a real dispatch tree

[4ndreello]

Summary

Every session in a run shared one runId, the open session's id. When a worker ran codedeck run itself, the child inherited that same CODEDECK_RUN_ID. The agents pane showed every worker as a direct child of a card with a hardcoded "Orchestrator" label. So a reviewer started by a general worker looked like the root had started it.

This PR records lineage and draws it as a tree.

• Store: new parent_id and role columns on sessions. They are added to existing databases through addMissingColumns.
• codedeck run: sends parentId, taken from CODEDECK_SESSION_ID (which every worker harness already has) or else CODEDECK_RUN_ID, plus role = parseRole(--role).
• open: sets CODEDECK_SESSION_ID to its own id and sends its role on session.adopt.
• Daemon: records parentId only when that session exists in the store. When the request has no runId, it inherits the parent's.
• Pane (plugin/mods/agents/pane.ts):
  • Each card hangs from its dispatcher, joined by elbow connectors.
  • The root card shows the open session's role and falls back to "Orchestrator".
  • Worker cards show their role.
  • A finished worker stays a card while any descendant is live.
  • History lines show ← parent.
  • When the pane is short, a card is evicted only after its children.
  • A parent missing from the snapshot, or a parent loop, falls back to the root.

Spec: .specs/features/worker-lineage/spec.md.

┌──────────────────────┐
│  General             │
└─┬────────────────────┘
  │ ┌───────────────────────────┐
  └─┤  a1b2  General · Claude   │
    └─┬─────────────────────────┘
      │ ┌─────────────────────────┐
      └─┤  c3d4  Reviewer · Codex │
        └─────────────────────────┘

Notes

• Sessions created before this change have no parentId, so the pane draws them under the root.
• Three existing pane tests change their height thresholds because the tree no longer spends a stem line between cards.
• Out of scope: moving reviewer dispatch into the harness, and the web console canvas.

Test plan

• npm run build
• New tests pass: tests/daemon-lineage.test.ts, the lineage cases in tests/mods-agents/pane.test.ts, and the parent/role cases in tests/run-role.test.ts
• Full vitest run: 1573/1574. The one failure, in tests/open-claude-probes.test.ts, fails the same way on the base branch
• scripts/pty-gate.sh

🤖 Generated with Claude Code

https://claude.ai/code/session_01QuWLN5K2HAo94s16Bb9HRU

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
2.2% Duplication on New Code

See analysis details on SonarQube Cloud