feat(backend): implement postgres job queue

backend/jobs/serializers.py

@@ -0,0 +1,71 @@
+from django.conf import settings
+from rest_framework import serializers
+
+from jobs.models import Job, JobEvent
+
+
+class JobSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Job
+        fields = (
+            "id",
+            "type",
+            "payload",
+            "status",
+            "priority",
+            "available_at",
+            "attempts",
+            "max_attempts",
+            "idempotency_key",
+            "locked_by",
+            "locked_until",
+            "last_error",
+            "result",
+            "created_at",
+            "updated_at",
+            "finished_at",
+        )
+        read_only_fields = (
+            "id",
+            "status",
+            "attempts",
+            "locked_by",
+            "locked_until",
+            "last_error",
+            "result",
+            "created_at",
+            "updated_at",
+            "finished_at",
+        )
+
+
+class JobCreateSerializer(serializers.Serializer):
+    type = serializers.CharField(max_length=120)
+    payload = serializers.JSONField(required=False, default=dict)
+    priority = serializers.IntegerField(required=False, min_value=-32768, max_value=32767, default=50)
+    available_at = serializers.DateTimeField(required=False, allow_null=True, default=None)
+    max_attempts = serializers.IntegerField(
+        required=False,
+        min_value=1,
+        default=lambda: settings.JOB_WORKER_MAX_ATTEMPTS_DEFAULT,
+    )
+    idempotency_key = serializers.CharField(
+        required=False,
+        allow_blank=True,
+        allow_null=True,
+        max_length=255,
+        default=None,
+    )
+
+    def validate_idempotency_key(self, value):
+        if value is None:
+            return None
+        value = value.strip()
+        return value or None
+
+
+class JobEventSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = JobEvent
+        fields = ("id", "job", "type", "attempt", "worker_id", "message", "data", "created_at")
+        read_only_fields = fields