feat(phase-1.2): temporal SDK client, worker mgmt, k8s deployments

- internal/temporal/client.go: robust client with retry + TLS + health check
- internal/temporal/worker.go: worker creation, registration, lifecycle
- internal/temporal/context.go: timeout helpers
- k8s/worker-deployment.yaml: 2-10 replica HPA, health probes, security context
- k8s/workflow-runner-deployment.yaml: singleton runner with probes
- k8s/kustomization.yaml: updated resource list, removed missing ref

Tests: 11 pass (client_test.go + worker_test.go)
Build: go build ./... clean
Kustomize: dry-run validated

internal/temporal/worker_test.go

@@ -0,0 +1,55 @@
+package temporal
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWorkerConfigDefaults(t *testing.T) {
+	cfg := WorkerConfig{}
+
+	// Verify defaults are applied in NewWorker
+	// (since we modify config in NewWorker, we just verify empty config is accepted)
+	assert.Equal(t, "", cfg.TaskQueue)
+	assert.Equal(t, 0, cfg.MaxConcurrentActivity)
+	assert.Equal(t, 0, cfg.MaxConcurrentWorkflow)
+	assert.Equal(t, "", cfg.Identity)
+}
+
+func TestRegisterWorkflowWithNilWorker(t *testing.T) {
+	err := RegisterWorkflow(nil, func() {})
+	assert.Error(t, err)
+	assert.Equal(t, "worker is nil", err.Error())
+}
+
+func TestRegisterActivityWithNilWorker(t *testing.T) {
+	err := RegisterActivity(nil, func() {})
+	assert.Error(t, err)
+	assert.Equal(t, "worker is nil", err.Error())
+}
+
+func TestRunWorkerWithNilWorker(t *testing.T) {
+	err := RunWorker(nil)
+	assert.Error(t, err)
+	assert.Equal(t, "worker is nil", err.Error())
+}
+
+func TestStopWorkerWithNilWorker(t *testing.T) {
+	// Should not panic
+	StopWorker(nil)
+}
+
+func TestWorkerConfigCustomValues(t *testing.T) {
+	cfg := WorkerConfig{
+		TaskQueue:             "custom-queue",
+		MaxConcurrentActivity: 20,
+		MaxConcurrentWorkflow: 30,
+		Identity:              "custom-identity",
+	}
+
+	assert.Equal(t, "custom-queue", cfg.TaskQueue)
+	assert.Equal(t, 20, cfg.MaxConcurrentActivity)
+	assert.Equal(t, 30, cfg.MaxConcurrentWorkflow)
+	assert.Equal(t, "custom-identity", cfg.Identity)
+}