[YayoiNanoka]

Summary

• add independent Agent and Plan collaboration modes, with a read-only Plan tool surface and structured SubmitPlan handoff
• persist proposal approval, revision, execution, interruption, resume, cancellation, and step progress while enforcing one active execution per session
• add the composer Plan switch, historical proposal cards, and a collapsible execution card with resume and abandon actions
• require plain-text step titles and descriptions, showing full details during review and compact titles during execution
• harden runtime event projection and shell-run hydration for structured Plan tool results

Verification

• npm --workspace @maka/core run build
• npm --workspace @maka/storage run build
• npm --workspace @maka/runtime run build
• npm --workspace @maka/desktop run typecheck
• Plan/Runtime/Storage/Desktop targeted suite: 54 tests passed
• npm --workspace @maka/ui test: 199 tests passed
• npm --workspace @maka/desktop run test:checks
• npm --workspace @maka/desktop run build:renderer

Review focus

This branch was intentionally based on feat/runtime-sandbox-diagnostics, so the PR also contains commit b14c7174, which exposes active sandbox diagnostics used by the runtime foundation.

PlanStepDefinition now requires a short plain-text title alongside its detailed description. Plan Mode has not shipped, so no migration for earlier local test data is included.