Add QA evidence for integration action loop

[Dkm0315]

Summary

• records integration action completion and integration_next continuity in the channel_plugin_setup QA artifact
• folds operator/action cases into cases.jsonl so strict release validation can see them
• adds strict required cases for the guided integration action loop

Validation

• pnpm exec tsx --test packages/cli/test/cli.test.ts
• pnpm --filter @musterhq/cli build
• pnpm exec tsx --test packages/core/test/qa-pack-readiness.test.ts packages/core/test/capability.test.ts
• smoke: muster qa run channel_plugin_setup ... shows integration_action_completion and integration_action_next_steps passed
• smoke: muster qa scorecard --strict-release ... shows strict.channel_plugin_setup passed with 17 cases