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-python/references/pattern-idempotency.md

@@ -0,0 +1,52 @@
+---
+title: Use Workflow IDs for Idempotency
+impact: MEDIUM
+impactDescription: Prevents duplicate executions of critical operations
+tags: idempotency, workflow-id, deduplication, exactly-once
+---
+
+## Use Workflow IDs for Idempotency
+
+Set workflow IDs to make operations idempotent. A workflow with the same ID executes only once.
+
+**Incorrect (duplicate payments possible):**
+
+```python
+@app.post("/pay/{order_id}")
+def process_payment(order_id: str):
+    # Multiple clicks = multiple payments!
+    handle = DBOS.start_workflow(payment_workflow, order_id)
+    return handle.get_result()
+```
+
+**Correct (idempotent with workflow ID):**
+
+```python
+from dbos import SetWorkflowID
+
+@app.post("/pay/{order_id}")
+def process_payment(order_id: str):
+    # Same order_id = same workflow ID = only one execution
+    with SetWorkflowID(f"payment-{order_id}"):
+        handle = DBOS.start_workflow(payment_workflow, order_id)
+    return handle.get_result()
+
+@DBOS.workflow()
+def payment_workflow(order_id: str):
+    charge_customer(order_id)
+    send_confirmation(order_id)
+    return "success"
+```
+
+Access the workflow ID inside workflows:
+
+```python
+@DBOS.workflow()
+def my_workflow():
+    current_id = DBOS.workflow_id
+    DBOS.logger.info(f"Running workflow {current_id}")
+```
+
+Workflow IDs must be globally unique. Duplicate IDs return the existing workflow's result without re-executing.
+
+Reference: [Workflow IDs and Idempotency](https://docs.dbos.dev/python/tutorials/workflow-tutorial#workflow-ids-and-idempotency)