task_local context over context objects

- interner impls logically separate from API in orchid-base (default host interner still in base for testing)
- error reporting, logging, and a variety of other features passed down via context in extension, not yet in host to maintain library-ish profile, should consider options
- no global spawn mechanic, the host has a spawn function but extensions only get a stash for enqueuing async work in sync callbacks which is then explicitly, manually, and with strict order popped and awaited
- still deadlocks nondeterministically for some ungodly reason

orchid-base/src/format.rs

@@ -304,6 +304,7 @@ pub async fn take_first_fmt(v: &(impl Format + ?Sized)) -> String {
 	take_first(&v.print(&FmtCtxImpl { _foo: PhantomData }).await, false)
 }
 
+#[derive(Default)]
 pub struct FmtCtxImpl<'a> {
 	_foo: PhantomData<&'a ()>,
 }
@@ -331,8 +332,8 @@ impl Format for Never {
 /// Format with default strategy. Currently equal to [take_first_fmt]
 pub async fn fmt(v: &(impl Format + ?Sized)) -> String { take_first_fmt(v).await }
 /// Format a sequence with default strategy. Currently equal to [take_first_fmt]
-pub async fn fmt_v<F: Format + ?Sized, R: Borrow<F>>(
-	v: impl IntoIterator<Item = R>,
+pub async fn fmt_v<F: Format + ?Sized>(
+	v: impl IntoIterator<Item: Borrow<F>>,
 ) -> impl Iterator<Item = String> {
 	join_all(v.into_iter().map(|f| async move { take_first_fmt(f.borrow()).await })).await.into_iter()
 }