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/workflow-determinism.md

@@ -0,0 +1,51 @@
+---
+title: Keep Workflows Deterministic
+impact: CRITICAL
+impactDescription: Non-deterministic workflows cannot recover correctly
+tags: workflow, determinism, recovery, reliability
+---
+
+## Keep Workflows Deterministic
+
+Workflow functions must be deterministic: given the same inputs and step return values, they must invoke the same steps in the same order. Non-deterministic operations must be moved to steps.
+
+**Incorrect (non-deterministic workflow):**
+
+```go
+func exampleWorkflow(ctx dbos.DBOSContext, input string) (string, error) {
+	// Random value in workflow breaks recovery!
+	// On replay, rand.Intn returns a different value,
+	// so the workflow may take a different branch.
+	if rand.Intn(2) == 0 {
+		return stepOne(ctx)
+	}
+	return stepTwo(ctx)
+}
+```
+
+**Correct (non-determinism in step):**
+
+```go
+func exampleWorkflow(ctx dbos.DBOSContext, input string) (string, error) {
+	// Step result is checkpointed - replay uses the saved value
+	choice, err := dbos.RunAsStep(ctx, func(ctx context.Context) (int, error) {
+		return rand.Intn(2), nil
+	}, dbos.WithStepName("generateChoice"))
+	if err != nil {
+		return "", err
+	}
+	if choice == 0 {
+		return stepOne(ctx)
+	}
+	return stepTwo(ctx)
+}
+```
+
+Non-deterministic operations that must be in steps:
+- Random number generation
+- Getting current time (`time.Now()`)
+- Accessing external APIs (`http.Get`, etc.)
+- Reading files
+- Database queries
+
+Reference: [Workflow Determinism](https://docs.dbos.dev/golang/tutorials/workflow-tutorial#determinism)