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.go

@@ -0,0 +1,84 @@
+package temporal
+
+import (
+	"fmt"
+
+	"go.temporal.io/sdk/client"
+	"go.temporal.io/sdk/worker"
+)
+
+// WorkerConfig holds configuration for worker creation.
+type WorkerConfig struct {
+	TaskQueue         string
+	MaxConcurrentActivity int
+	MaxConcurrentWorkflow int
+	Identity          string
+}
+
+// NewWorker creates a new Temporal worker with production-ready configuration.
+//
+// Features:
+// - Automatic task queue setup
+// - Configurable concurrency limits
+// - Activity and workflow registration
+// - Structured error handling
+func NewWorker(c client.Client, cfg WorkerConfig) (worker.Worker, error) {
+	if cfg.TaskQueue == "" {
+		cfg.TaskQueue = "poimen-taskqueue"
+	}
+	if cfg.MaxConcurrentActivity == 0 {
+		cfg.MaxConcurrentActivity = 10
+	}
+	if cfg.MaxConcurrentWorkflow == 0 {
+		cfg.MaxConcurrentWorkflow = 10
+	}
+	if cfg.Identity == "" {
+		cfg.Identity = "poimen-worker-default"
+	}
+
+	workerOptions := worker.Options{
+		Identity:                 cfg.Identity,
+		MaxConcurrentActivityExecutionSize: cfg.MaxConcurrentActivity,
+		MaxConcurrentWorkflowTaskExecutionSize: cfg.MaxConcurrentWorkflow,
+	}
+
+	w := worker.New(c, cfg.TaskQueue, workerOptions)
+	if w == nil {
+		return nil, fmt.Errorf("failed to create worker for task queue: %s", cfg.TaskQueue)
+	}
+
+	return w, nil
+}
+
+// RegisterWorkflow registers a workflow with the worker.
+func RegisterWorkflow(w worker.Worker, workflow interface{}) error {
+	if w == nil {
+		return fmt.Errorf("worker is nil")
+	}
+	w.RegisterWorkflow(workflow)
+	return nil
+}
+
+// RegisterActivity registers an activity with the worker.
+func RegisterActivity(w worker.Worker, activity interface{}) error {
+	if w == nil {
+		return fmt.Errorf("worker is nil")
+	}
+	w.RegisterActivity(activity)
+	return nil
+}
+
+// RunWorker starts the worker and blocks until shutdown or error.
+func RunWorker(w worker.Worker) error {
+	if w == nil {
+		return fmt.Errorf("worker is nil")
+	}
+	return w.Run(worker.InterruptCh())
+}
+
+// StopWorker gracefully stops the worker.
+func StopWorker(w worker.Worker) {
+	if w != nil {
+		w.Stop()
+	}
+}