[codex] Complete M11.5 consolidation

[roackb2]

Summary

This PR completes the M11.5 consolidation pass from the domain-module retro. It turns the prior structural refactor into materially cleaner architecture instead of leaving thin wrappers and half-adopted seams.

• Finish command-boundary cleanup already present on the branch: slash autocomplete delegates to core helpers, command result types live in the command domain, and command docs describe current behavior.
• Consolidate observability/activity projection: remove duplicated tool summary logic, delete the one-line core/chat/trace-summary.ts wrapper, carry runId/step/timestamp correlation metadata through projected conversation activities, and keep TUI/web adapters on typed activity handler maps.
• Make approval policy a real runtime extension seam: add approvalPolicies through runAgent, runAgentLoop, heartbeat, session submit, and ordinary chat turns; let built-in request policies be satisfied by remembered/custom policies before falling through to human approval; move TUI remembered approvals into the policy layer.
• Make trace summarizer registration real in production: chat turn persistence can now use a supplied TraceSummarizerRegistry instead of always using the default summarizer.
• Add import-boundary tests for core-to-host layering, command UI independence, and approval host independence.
• Update approvals, observability, and chat docs to reflect the current ownership boundaries.

Why

The retro found that M0-M11 improved structure but did not fully reach the desired architectural outcome. This PR is the consolidation step: it removes fake seams, adopts the extension points in production paths, and adds guardrails so the same layering problems do not quietly return.

Validation

• yarn test:unit
• yarn typecheck
• yarn eslint
• yarn vitest run src/__tests__/integration/core/run-agent.test.ts
• yarn vitest run src/__tests__/integration/web/control-plane-sessions-state.test.tsx
• git diff --check

Note: earlier, yarn test:integration src/__tests__/integration/web/control-plane-sessions-state.test.tsx expanded to the full integration suite in this repo. The broader run failed in unrelated sandbox/setup areas: temp git commits without identity and daemon tests blocked from listening on 127.0.0.1. The exact web test passed when run directly with Vitest.

[chatgpt-codex-connector]

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