Resolve #2287: allow nested CQRS publishes to drain

[ayden94]

Summary

Allow nested CQRS publish(...) and publishAll(...) calls from active handler/saga pipelines to continue draining after shutdown starts while continuing to reject brand-new external publishes.

Linked context: Closes #2287

Changes

• Added an internal CQRS dispatch-context marker shared by saga and event-bus shutdown guards.
• Track active publish drain contexts so only context-preserving nested publishes can run while the event bus is stopping.
• Extended CQRS shutdown regression coverage for nested handler publishes, nested saga publishAll(...), and stale-context rejection.
• Updated CQRS README and architecture docs in English/Korean, plus a patch changeset for @fluojs/cqrs.

Testing

• pnpm exec biome check packages/cqrs/src/dispatch-context.ts packages/cqrs/src/buses/event-bus.ts packages/cqrs/src/buses/saga-bus.ts packages/cqrs/src/module.test.ts packages/cqrs/README.md packages/cqrs/README.ko.md docs/architecture/cqrs.md docs/architecture/cqrs.ko.md .changeset/tame-cqrs-drain.md
• pnpm --filter @fluojs/cqrs... build
• pnpm --filter @fluojs/cqrs typecheck
• pnpm --filter @fluojs/cqrs test
• pnpm docs:sync-check
• pnpm verify:platform-consistency-governance
• pnpm verify:changeset-release-lane
• pnpm verify:release-readiness was attempted; it failed in unrelated existing/infra-sensitive suites (packages/cron/src/optional-redis-peer.test.ts timeout and packages/testing/src/surface.test.ts timeout/unhandled rejection while rebuilding @fluojs/di against missing @fluojs/core declarations).

Release impact

• This PR has consumer-visible release impact and includes a changeset.
• This PR has no consumer-visible release impact.

Public export documentation

• Changed public exports include a source-level summary.
• Changed exported functions document matching @param / @returns tags where applicable.
• Source @example blocks and README scenario examples still play complementary roles.

Behavioral contract

• No documented behavioral contracts were removed without migration notes.
• New behavioral contracts are documented in the affected package README.
• Intentional limitations are explicitly stated (not silently removed).
• Runtime invariants are covered by regression tests.

Platform consistency governance (SSOT)

• SSOT English/Korean mirror structure remains synchronized for changed governance docs.
• If platform contract docs changed, companion updates include discoverability/docs index, tooling or CI enforcement, and regression-test evidence.
• Any package README alignment/conformance claims are backed by createPlatformConformanceHarness(...) tests.