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/client_test.go

@@ -0,0 +1,62 @@
+package temporal
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestClientConfigDefaults(t *testing.T) {
+	cfg := ClientConfig{}
+
+	// Verify defaults are applied in NewClient
+	// (since we modify config in NewClient)
+	assert.Equal(t, "", cfg.HostPort)
+	assert.Equal(t, "", cfg.Namespace)
+}
+
+func TestNewClientConnectionFailure(t *testing.T) {
+	cfg := ClientConfig{
+		HostPort:    "localhost:9999", // Non-existent port
+		Namespace:   "test",
+		MaxRetries:  1,
+		DialTimeout: 100 * time.Millisecond,
+	}
+
+	client, err := NewClient(cfg)
+	assert.Error(t, err)
+	assert.Nil(t, client)
+	assert.Contains(t, err.Error(), "failed to connect to Temporal")
+}
+
+func TestContextWithTimeout(t *testing.T) {
+	ctx, cancel := ContextWithTimeout(5 * time.Second)
+	defer cancel()
+
+	assert.NotNil(t, ctx)
+	select {
+	case <-ctx.Done():
+		t.Fatal("context should not be done immediately")
+	default:
+		// Expected: context is still valid
+	}
+}
+
+func TestContextWithDefault(t *testing.T) {
+	ctx, cancel := ContextWithDefault()
+	defer cancel()
+
+	assert.NotNil(t, ctx)
+	select {
+	case <-ctx.Done():
+		t.Fatal("context should not be done immediately")
+	default:
+		// Expected: context is still valid
+	}
+}
+
+func TestCloseClientWithNilClient(t *testing.T) {
+	err := CloseClient(nil)
+	assert.NoError(t, err)
+}