- add heartbeat.go with heartbeatIntervalSecs var, SetHeartbeatInterval, runHeartbeat (no build tag, CGO-free)
- add heartbeat_test.go with 5 tests covering interval validation and goroutine lifecycle
- add StartHeartbeat to clib.go (CGO impl calling xcecli_heartbeat)
- remove SetHeartbeatInterval stub from stub.go (now real code in heartbeat.go)
- remove TestSetHeartbeatInterval_StubNoOp from stub_funcs_test.go
- call SetHeartbeatInterval in OnClusterUpdated to track backend-pushed interval
- call backend.StartHeartbeat in cmd/main.go after backend registration
Add four function stubs to backend/stub.go for the !cgo build path:
- StartHeartbeat(ctx context.Context) — no-op (heartbeat not available)
- SetHeartbeatInterval(secs int) — no-op (interval update not available)
- EvalSelectForHost(hostname, selectExpr string) error — returns errNoCGO
- Cleanup() — no-op (no C resources to release without CGO)
TDD: four tests in stub_funcs_test.go verify stubs behave correctly
(no-op functions don't panic, error stubs return errNoCGO). All backend
tests passing.
