feat(neon): Add typescript-ordermap feature

Adds a `typescript-ordermap` feature flag that provides a TypeScript
impl for `ordermap::OrderMap<K, V>`, mapping to `Record<K, V>` (same
as `HashMap` and `BTreeMap`).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dherman

Cargo.lock

@@ -40,6 +40,7 @@ serde = { version = "1.0.197", optional = true }
 serde_json = { version = "1.0.114", optional = true }
 chrono = { version = "0.4", optional = true, default-features = false }
 uuid = { version = "1", optional = true }
+ordermap = { version = "1", optional = true }
 
 [dependencies.tokio]
 version = "1.34.0"
@@ -63,6 +64,9 @@ typescript-chrono = ["typescript", "dep:chrono"]
 # TypeScript impl for uuid::Uuid (→ string)
 typescript-uuid = ["typescript", "dep:uuid"]
 
+# TypeScript impl for ordermap::OrderMap<K, V> (→ Record<K, V>)
+typescript-ordermap = ["typescript", "dep:ordermap"]
+
 # Enable the creation of external binary buffers. This is disabled by default
 # since these APIs fail at runtime in environments that enable the V8 memory
 # cage (such as Electron: https://www.electronjs.org/blog/v8-memory-cage).

crates/neon/Cargo.toml

@@ -445,6 +445,22 @@ impl TypeScript for uuid::Uuid {
     }
 }
 
+// ——— OrderMap ———
+
+#[cfg(feature = "typescript-ordermap")]
+impl<K: TypeScript, V: TypeScript> TypeScript for ordermap::OrderMap<K, V> {
+    fn ts_type() -> Cow<'static, str> {
+        let k = K::ts_type();
+        let v = V::ts_type();
+        format!("Record<{k}, {v}>").into()
+    }
+
+    fn ts_collect(decls: &mut BTreeMap<String, String>) {
+        K::ts_collect(decls);
+        V::ts_collect(decls);
+    }
+}
+
 // ——— Serde JSON wrapper ———
 
 #[cfg(feature = "serde")]

crates/neon/src/typescript.rs

@@ -353,7 +353,7 @@ When an export uses a type from an external crate (e.g., `chrono::DateTime`,
 that type. There are three mechanisms to handle this:
 
 1. **Built-in impls behind feature flags.** Neon can ship `TypeScript` implementations
-   for popular crates: `neon = { features = ["typescript-chrono", "typescript-uuid"] }`.
+   for popular crates: `neon = { features = ["typescript-chrono", "typescript-uuid", "typescript-ordermap"] }`.
    Each impl is a few lines mapping to the obvious TS type.
 
 2. **Manual trait implementation.** Users can implement `TypeScript` for any type in