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-scheduled.md

@@ -0,0 +1,69 @@
+---
+title: Create Scheduled Workflows
+impact: MEDIUM
+impactDescription: Enables recurring tasks with exactly-once-per-interval guarantees
+tags: pattern, scheduled, cron, recurring
+---
+
+## Create Scheduled Workflows
+
+Use `dbos.WithSchedule` when registering a workflow to run it on a cron schedule. Each scheduled invocation runs exactly once per interval.
+
+**Incorrect (manual scheduling with goroutine):**
+
+```go
+// Manual scheduling is not durable and misses intervals during downtime
+go func() {
+	for {
+		generateReport()
+		time.Sleep(60 * time.Second)
+	}
+}()
+```
+
+**Correct (using WithSchedule):**
+
+```go
+// Scheduled workflow must accept time.Time as input
+func everyThirtySeconds(ctx dbos.DBOSContext, scheduledTime time.Time) (string, error) {
+	fmt.Println("Running scheduled task at:", scheduledTime)
+	return "done", nil
+}
+
+func dailyReport(ctx dbos.DBOSContext, scheduledTime time.Time) (string, error) {
+	_, err := dbos.RunAsStep(ctx, func(ctx context.Context) (string, error) {
+		return generateReport()
+	}, dbos.WithStepName("generateReport"))
+	return "report generated", err
+}
+
+func main() {
+	ctx, _ := dbos.NewDBOSContext(context.Background(), config)
+	defer dbos.Shutdown(ctx, 30*time.Second)
+
+	dbos.RegisterWorkflow(ctx, everyThirtySeconds,
+		dbos.WithSchedule("*/30 * * * * *"),
+	)
+	dbos.RegisterWorkflow(ctx, dailyReport,
+		dbos.WithSchedule("0 0 9 * * *"), // 9 AM daily
+	)
+
+	dbos.Launch(ctx)
+	select {} // Block forever
+}
+```
+
+Scheduled workflows must accept exactly one parameter of type `time.Time` representing the scheduled execution time.
+
+DBOS crontab uses 6 fields with second precision:
+```text
+┌────────────── second
+│ ┌──────────── minute
+│ │ ┌────────── hour
+│ │ │ ┌──────── day of month
+│ │ │ │ ┌────── month
+│ │ │ │ │ ┌──── day of week
+* * * * * *
+```
+
+Reference: [Scheduled Workflows](https://docs.dbos.dev/golang/tutorials/workflow-tutorial#scheduled-workflows)