feat: add jobs worker and webhook core

contracts/jobs/jobs-v1.json

@@ -0,0 +1,44 @@
+{
+  "version": 1,
+  "statuses": ["queued", "running", "succeeded", "failed", "expired", "cancelled"],
+  "terminalStatuses": ["succeeded", "failed", "expired", "cancelled"],
+  "idempotency": {
+    "scope": ["ownerId", "externalClientId", "idempotencyKey"],
+    "body": {
+      "settings": { "width": 1024, "height": 768 },
+      "prompt": "hello",
+      "idempotencyKey": "body-key",
+      "capability": "image.generate"
+    },
+    "fingerprintSource": {
+      "capability": "image.generate",
+      "prompt": "hello",
+      "settings": { "height": 768, "width": 1024 }
+    },
+    "fingerprint": "3ac3128766c0bdac36627b996cb5b3b1ed752794989d559c24f6621988e51a03",
+    "conflictStatus": 409,
+    "reusedStatus": 200,
+    "createdStatus": 202
+  },
+  "priority": { "minimum": -100, "maximum": 100, "default": 0 },
+  "publicList": { "defaultLimit": 50, "minimumLimit": 1, "maximumLimit": 200 },
+  "claim": { "minimumBatch": 1, "maximumBatch": 20, "defaultLockTimeoutSeconds": 300 },
+  "retry": {
+    "defaultMaxAttempts": 3,
+    "baseDelayMilliseconds": 10000,
+    "maximumDelayMilliseconds": 300000,
+    "cases": [
+      { "attemptsBefore": 0, "retryable": true, "delayMilliseconds": 10000, "action": "retry_scheduled" },
+      { "attemptsBefore": 1, "retryable": true, "delayMilliseconds": 20000, "action": "retry_scheduled" },
+      { "attemptsBefore": 2, "retryable": true, "delayMilliseconds": 40000, "action": "retry_scheduled" },
+      { "attemptsBefore": 3, "retryable": true, "action": "processed" },
+      { "attemptsBefore": 0, "retryable": false, "action": "processed" }
+    ]
+  },
+  "cancel": {
+    "idempotentTerminal": true,
+    "activeResult": "cancelled",
+    "clearsLease": true,
+    "refundKey": "job-refund:{jobId}"
+  }
+}

contracts/webhook/job-webhook-v1.json

@@ -0,0 +1,18 @@
+{
+  "version": 1,
+  "maximumAttempts": 3,
+  "contentType": "application/json",
+  "userAgent": "zhinian-aigc-webhook/1.0",
+  "signatureHeader": "X-Zhinian-Signature",
+  "secret": "webhook-secret",
+  "job": {
+    "id": "job-1",
+    "status": "failed",
+    "capability": "image.generate",
+    "outputAssetIds": [],
+    "error": { "message": "provider unavailable", "retryable": true },
+    "updatedAt": "2026-08-13T08:00:00.000Z"
+  },
+  "body": "{\"jobId\":\"job-1\",\"status\":\"failed\",\"capability\":\"image.generate\",\"outputAssetIds\":[],\"error\":{\"message\":\"provider unavailable\",\"retryable\":true},\"updatedAt\":\"2026-08-13T08:00:00.000Z\"}",
+  "signature": "sha256=32b8fd385692f6f549c0b1e1ffc9dce404c7a3a9a0aa19ca45225ad257d94411"
+}