fix(isolated-declarations): incorrect nested namespace output in isolated declarations

crates/oxc_isolated_declarations/src/declaration.rs

@@ -129,8 +129,8 @@ impl<'a> IsolatedDeclarations<'a> {
         // Follows https://github.com/microsoft/TypeScript/pull/54134
         let kind = TSModuleDeclarationKind::Namespace;
         match body {
-            TSModuleDeclarationBody::TSModuleDeclaration(decl) => {
-                let inner = self.transform_ts_module_declaration(decl);
+            TSModuleDeclarationBody::TSModuleDeclaration(inner_decl) => {
+                let inner = self.transform_ts_module_declaration(inner_decl);
                 self.ast.alloc_ts_module_declaration(
                     decl.span,
                     decl.id.clone_in(self.ast.allocator),

crates/oxc_isolated_declarations/tests/fixtures/nested-namespace-dotted.ts

@@ -0,0 +1,15 @@
+// Dotted namespace syntax should preserve all names correctly
+export namespace X.Y.Z {}
+
+// Nested dotted namespaces with content
+export namespace A.B.C {
+    export const value = 1;
+    export function foo(): void {}
+}
+
+// Deeply nested
+export namespace Deep.Nested.Namespace.Structure {
+    export interface Config {
+        value: string;
+    }
+}

crates/oxc_isolated_declarations/tests/snapshots/nested-namespace-dotted.snap

@@ -0,0 +1,22 @@
+---
+source: crates/oxc_isolated_declarations/tests/mod.rs
+input_file: crates/oxc_isolated_declarations/tests/fixtures/nested-namespace-dotted.ts
+---
+```
+==================== .D.TS ====================
+
+// Dotted namespace syntax should preserve all names correctly
+export declare namespace X.Y.Z {
+	export {};
+}
+// Nested dotted namespaces with content
+export declare namespace A.B.C {
+	const value = 1;
+	function foo(): void;
+}
+// Deeply nested
+export declare namespace Deep.Nested.Namespace.Structure {
+	interface Config {
+		value: string;
+	}
+}