Add the core execution types needed for the async refactor (#4390)

* Add the core execution types, the borrowed context, and the seeded u64 fx hasher

* Fix frame table key aliasing and arena handle offset truncation

* Drop arena entries in reverse allocation order and require Send + Sync payloads

* Draw arena generations from a global counter so foreign handles never upgrade

* Forward serialize through node wrappers and free abandoned frame table reservations

* Make arena generation exhaustion fallible with an unsafe counter rewind

* Guard the shared generation counter in tests and reject oversized batch ranges

* Park the arena during drop glue, guard filled batches, and normalize deserialized sources

* Make the sources fields private and normalize them on every mutation

* Remove the unused CtxSnapshot scope reconstruction

node-graph/graph-craft/src/document/value.rs

@@ -309,6 +309,7 @@ macro_rules! tagged_value {
 			pub fn from_type(input: &Type) -> Option<Self> {
 				match input {
 					Type::Generic(_) => None,
+					Type::Ref(_) => None,
 					Type::Concrete(concrete_type) => {
 						let name = concrete_type.name.as_ref();
 						// TODO: Add default implementations for types such as TaggedValue::Subpaths, and use the defaults here and in document_node_types
@@ -569,6 +570,7 @@ impl TaggedValue {
 
 		match ty {
 			Type::Generic(_) => None,
+			Type::Ref(_) => None,
 			Type::Concrete(concrete_type) => {
 				let ty = concrete_type.id?;
 				use std::any::TypeId;