docs: residual handoff as work records (role, not kind)

Canon work-record-types: residuals use intake/workplan/decision with
origin residual|handoff and origin_ref parent WP. Schema origin_ref;
agent close protocol aligned.

canon/standards/schemas/work-records/intake.schema.json

@@ -17,7 +17,14 @@
     "priority": { "enum": ["high", "medium", "low"] },
     "pulls_from": { "type": "array" },
     "promoted_to": { "type": "string", "description": "Canonical id of the record this intake was promoted to." },
-    "origin": { "type": "string" },
+    "origin": {
+      "type": "string",
+      "description": "Where the spark came from. Residuals use residual|handoff; also e.g. legacy-suggestion:<uuid>, mail-triage ids."
+    },
+    "origin_ref": {
+      "type": "string",
+      "description": "Stable reference into the origin (parent workplan id for residuals, e.g. BINKY-WP-0006)."
+    },
     "notes": { "type": "string" },
     "state_hub_intake_id": { "$ref": "spine.schema.json#/$defs/uuid" }
   },