C#: receipt server follows Heimdall's review of #61

Look the id up first and authorize only on first sighting; remember refusals within the cap; never re-forward an id whose primary stayed silent; end the connection when an answer cannot be queued; fixed refusal texts; limit_reached cap refusal; commit-point doc on ApplyPut/Delete.

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

src/GameCult.Networking/CultNetDatabase.cs

@@ -1017,6 +1017,8 @@ namespace GameCult.Networking
         /// <summary>
         /// Applies a raw document mutation after checking shard authority. This is the host's own door (and replication's):
         /// it asks no remote write authority. A peer's put goes through <see cref="CultNetDatabaseServer"/>, which does.
+        /// Returning normally means the put is committed and visible to readers: a receipt-capable peer is told
+        /// <c>write_admitted</c> on the strength of it, so a write that has only been queued must not return.
         /// </summary>
         /// <exception cref="CultNetUnownedSchemaException">No shard owns the schema and key; nothing was written.</exception>
         /// <exception cref="CultNetShardLogException">The change committed and was published, but the shard log could not record it.</exception>
@@ -1047,6 +1049,7 @@ namespace GameCult.Networking
         /// <summary>
         /// Applies a raw document delete after checking shard authority. This is the host's own door: it asks no remote
         /// write authority. A peer's delete goes through <see cref="CultNetDatabaseServer"/>, which does.
+        /// Returning normally means the delete is committed and visible to readers (see <see cref="ApplyPutAsync(CultNetDocumentPutRawMessage)"/>).
         /// </summary>
         /// <exception cref="CultNetUnownedSchemaException">No shard owns the schema and key; nothing was written.</exception>
         /// <exception cref="CultNetShardLogException">The change committed and was published, but the shard log could not record it.</exception>