feat: add DBOS skills for TypeScript, Python, and Go (#94)

Add three DBOS SDK skills with reference documentation for building
reliable, fault-tolerant applications with durable workflows.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

skills/dbos-golang/references/pattern-idempotency.md

@@ -0,0 +1,63 @@
+---
+title: Use Workflow IDs for Idempotency
+impact: MEDIUM
+impactDescription: Prevents duplicate side effects like double payments
+tags: pattern, idempotency, workflow-id, deduplication
+---
+
+## Use Workflow IDs for Idempotency
+
+Assign a workflow ID to ensure a workflow executes only once, even if called multiple times. This prevents duplicate side effects like double payments.
+
+**Incorrect (no idempotency):**
+
+```go
+func processPayment(ctx dbos.DBOSContext, orderID string) (string, error) {
+	_, err := dbos.RunAsStep(ctx, func(ctx context.Context) (string, error) {
+		return chargeCard(orderID)
+	}, dbos.WithStepName("chargeCard"))
+	return "charged", err
+}
+
+// Multiple calls could charge the card multiple times!
+dbos.RunWorkflow(ctx, processPayment, "order-123")
+dbos.RunWorkflow(ctx, processPayment, "order-123") // Double charge!
+```
+
+**Correct (with workflow ID):**
+
+```go
+func processPayment(ctx dbos.DBOSContext, orderID string) (string, error) {
+	_, err := dbos.RunAsStep(ctx, func(ctx context.Context) (string, error) {
+		return chargeCard(orderID)
+	}, dbos.WithStepName("chargeCard"))
+	return "charged", err
+}
+
+// Same workflow ID = only one execution
+workflowID := fmt.Sprintf("payment-%s", orderID)
+dbos.RunWorkflow(ctx, processPayment, "order-123",
+	dbos.WithWorkflowID(workflowID),
+)
+dbos.RunWorkflow(ctx, processPayment, "order-123",
+	dbos.WithWorkflowID(workflowID),
+)
+// Second call returns the result of the first execution
+```
+
+Access the current workflow ID inside a workflow:
+
+```go
+func myWorkflow(ctx dbos.DBOSContext, input string) (string, error) {
+	currentID, err := dbos.GetWorkflowID(ctx)
+	if err != nil {
+		return "", err
+	}
+	fmt.Printf("Running workflow: %s\n", currentID)
+	return input, nil
+}
+```
+
+Workflow IDs must be **globally unique** for your application. If not set, a random UUID is generated.
+
+Reference: [Workflow IDs and Idempotency](https://docs.dbos.dev/golang/tutorials/workflow-tutorial#workflow-ids-and-idempotency)