Fix UUID cast in task creation, add kind test manifests

- Fix parent_task_id NULLIF cast to UUID type in INSERT query
- Fix itoa helper to use strconv.Itoa
- Handle AddReaction errors gracefully in webhook handler
- Add hack/kind/ manifests for local testing with kind cluster

hack/kind/manifests/postgres.yaml

@@ -0,0 +1,38 @@
+---
+apiVersion: v1
+kind: Pod
+metadata:
+  name: postgres
+  namespace: forgebot
+  labels:
+    app: postgres
+spec:
+  containers:
+    - name: postgres
+      image: postgres:17-alpine
+      env:
+        - name: POSTGRES_USER
+          value: forgebot
+        - name: POSTGRES_PASSWORD
+          value: forgebot
+        - name: POSTGRES_DB
+          value: forgebot
+      ports:
+        - containerPort: 5432
+      readinessProbe:
+        exec:
+          command: ["pg_isready", "-U", "forgebot"]
+        initialDelaySeconds: 5
+        periodSeconds: 5
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: postgres
+  namespace: forgebot
+spec:
+  selector:
+    app: postgres
+  ports:
+    - port: 5432
+      targetPort: 5432