refactor: use Object.assign with empty target to avoid mutation

Co-authored-by: stipsan <[email protected]>

Author: Copilot

packages/@sanity/pkg-utils/src/node/resolveBuildTasks.ts

@@ -14,7 +14,7 @@ export function resolveBuildTasks(ctx: BuildContext): BuildTask[] {
   const tasks: BuildTask[] = []
 
   const exports = Object.entries(ctx.exports || {}).map(
-    ([_path, exp]) => Object.assign(exp, {_path}) as PkgExport & {_path: string},
+    ([_path, exp]) => Object.assign({}, exp, {_path}) as PkgExport & {_path: string},
   )
 
   const dtsTask: DtsTask = {

packages/@sanity/pkg-utils/src/node/resolveWatchTasks.ts

@@ -11,7 +11,7 @@ export function resolveWatchTasks(ctx: BuildContext): WatchTask[] {
   const tasks: WatchTask[] = []
 
   const exports = Object.entries(ctx.exports || {}).map(
-    ([_path, exp]) => Object.assign(exp, {_path}) as PkgExport & {_path: string},
+    ([_path, exp]) => Object.assign({}, exp, {_path}) as PkgExport & {_path: string},
   )
 
   const dtsTask: DtsWatchTask = {