PRT-043 channel interaction runtime contracts

[deksden]

Summary

• adds PRT-043 command-framework contracts in @dd-bot-platform/core
• adds channel-runtime threading/delivery summary contracts
• materializes @dd-bot-platform/core@0.3.0 and @dd-bot-platform/channel-runtime@0.3.0 via Changesets
• records subagent reports and release/product-adoption blockers

Checks

• pnpm build
• pnpm changeset:publish --dry-run
• node --test packages/core/dist/command-framework.spec.js packages/channel-runtime/dist/channel-runtime.spec.js