cultnet-ts: the registry decodes the value a raw put would store

CultNetDocumentRegistry.decodeRawDocumentPut returns the binding and
value applyRawDocumentPutMessage would store for a raw put, so a server
can build the receipt that would acknowledge a put before storing it.
It throws, as the put would, when no binding accepts the document.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/cultnet-ts/src/replication.ts

@@ -268,6 +268,20 @@ export class CultNetDocumentRegistry {
     };
   }
 
+  /**
+   * The binding and value `applyRawDocumentPutMessage` would store for this raw
+   * put, decoded as that binding reads it. A server uses it to build the reply
+   * that would acknowledge the put before storing it. Throws, as the put would,
+   * when no binding accepts the document.
+   */
+  decodeRawDocumentPut(message: CultNetDocumentPutRawMessage): {
+    binding: CultNetDocumentBinding;
+    value: unknown;
+  } {
+    const { binding, envelope } = this.#rawPutEnvelope(message);
+    return { binding, value: decodeDocumentValue(binding.definition, envelope.payload) };
+  }
+
   #rawPutEnvelope(message: CultNetDocumentPutRawMessage): {
     binding: CultNetDocumentBinding;
     envelope: CultCacheEnvelope;