verify(P18): onboarding-schema-and-lambda-action — 4-layer verify PASS + ship

VERIFY: structural — schema + Lambda action; behavioral — 41 tests + CI PASS; quality — pending CMDB row (D-119, no AWS resources).

---ci---
project: acdl
phase: 18
milestone: v1.16
status: complete
phase_role: execution
requirements:
  covered: [REQ-182]
  partial: []
---/ci---

schemas/onboarding.schema.json

@@ -0,0 +1,39 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://nova.cloudinit.dev/schemas/onboarding.schema.json",
+  "title": "Nova Consumer Onboarding Request",
+  "description": "A self-service onboarding request from a consumer repo. Submitted to the contract_ingestor Lambda 'onboard_consumer' action (D-113, P18/REQ-182). The Lambda validates the payload against this schema, then writes a 'pending' CMDB row to nova-contracts. No AWS resources are created by this action (D-119); the cross-account role + ABAC tag grant is offline-proven Terraform (P20/REQ-184).",
+  "type": "object",
+  "required": ["consumerRepo", "requestedEnvironment", "ownerId", "billingTag"],
+  "additionalProperties": false,
+  "properties": {
+    "consumerRepo": {
+      "type": "string",
+      "description": "The consumer repository in org/repo format.",
+      "pattern": "^[a-zA-Z0-9_.-]+/[a-zA-Z0-9_.-]+$",
+      "maxLength": 128
+    },
+    "requestedEnvironment": {
+      "type": "string",
+      "description": "The environment the consumer requests (must exist as a core/environments/<name>.json).",
+      "enum": ["dev", "qa", "prod", "dr"]
+    },
+    "ownerId": {
+      "type": "string",
+      "description": "The owning team or individual (for ABAC nova:owner tag + CMDB).",
+      "minLength": 1,
+      "maxLength": 64
+    },
+    "billingTag": {
+      "type": "string",
+      "description": "The cost-center / billing tag for the consumer's resources.",
+      "minLength": 1,
+      "maxLength": 64
+    },
+    "notes": {
+      "type": "string",
+      "description": "Optional free-form notes for the platform team.",
+      "maxLength": 500
+    }
+  }
+}