feat(hris): EmployeeOnboarded broadcast / fan-out (Phase 5b)

[intech]

Draft — stacked on #31 (Phase 5a) and gated on the 1.1.0 release. Base is the Phase 5a branch, so this diff shows only the Phase 5b delta. Rebase onto main and retarget once #31 merges.

What

Adds the multi-subscriber face of the EventBus, completing the hris example's three-mechanism story (ctx.call · EventBus · Temporal saga). The onboarding saga's terminal step broadcasts EmployeeOnboarded ONCE, and three independent reactors consume it:

• welcome — "sends" a welcome email
• audit — appends an onboarding record (full message shape)
• headcount — tallies per-department headcount

saga COMPLETES ─▶ announceOnboarded (publish ONCE) ─▶ EmployeeOnboarded
                                                         ├─▶ welcome    (group hris-welcome)
                                                         ├─▶ audit      (group hris-audit)
                                                         └─▶ headcount  (group hris-headcount)

• publishes (1.1.0): the publish-only bus lists OnboardingEventHandlers in publishes, so the topic onboarding.employee-onboarded resolves from the proto option with no raw topic hand-passed (a route-less publisher otherwise falls back to the message typeName).
• Fan-out is four buses, not one: each reactor runs on its own bus with a distinct consumer group (the per-bus duplicate-topic guard forces this), so on a broker every reactor gets every event. Reactors are idempotent (dedupe by employeeId — broker broadcast is at-least-once). Each runs as its own process (node src/reactor.ts, role by REACTOR).
• Fire-and-forget: the broadcast runs outside the saga's compensation scope; a publish failure is logged, never rolled back — a lost broadcast must never undo a completed onboarding. The worker owns the publish-bus lifecycle and injects it via setPublisherBus.

Scope of verification (honest)

• Verified dockerless against the 1.1.0-shape (pkg.pr.new @165): typecheck clean, 37/37 tests (was 33 in feat(hris): durable onboarding saga (Temporal) — Phase 5a #31). New/updated: the broadcast fan-out (one publish → three reactors with the full shape), topic-from-proto-option, idempotency, and a broadcast-failure-tolerance workflow test (a failed broadcast still resolves COMPLETED, no compensation).
• The committed @connectum/* deps stay ^1.0.0 (no pkg.pr.new URLs); the verification override was local-only and is not in this diff.
• docker-compose.yml (the three reactor services + worker NATS wiring) is config-validated, not run.
• The existing LeaveApproved e2e is unchanged.

Gating

1. feat(hris): durable onboarding saga (Temporal) — Phase 5a #31 (Phase 5a) must merge first (this stacks on it).
2. 1.1.0 must publish — publishes / the broadcast wiring ship in 1.1.0; ^1.0.0 resolves it once on npm. This mirrors the car-sharing Phase 3 broadcast draft (feat(car-sharing): EventBus broadcast / fan-out on trip completion (Phase 3) #29).

🤖 Generated with Claude Code

https://claude.ai/code/session_01MdeH7fExPmiRHRirGuvGk3

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