fix(core): ensure edit and write-file tools use storage.getPlansDir

This fixes test failures introduced during conflict resolution by strictly calling storage.getPlansDir as per the new config architecture.

packages/core/src/tools/edit.ts

@@ -1058,7 +1058,7 @@ export class EditTool
       try {
         resolvedPath = resolveAndValidatePlanPath(
           params.file_path,
-          this.config.getPlansDir(),
+          this.config.storage.getPlansDir(),
         );
       } catch (err) {
         return err instanceof Error ? err.message : String(err);

packages/core/src/tools/write-file.ts

@@ -504,7 +504,7 @@ export class WriteFileTool
       try {
         resolvedPath = resolveAndValidatePlanPath(
           filePath,
-          this.config.getPlansDir(),
+          this.config.storage.getPlansDir(),
         );
       } catch (err) {
         return err instanceof Error ? err.message : String(err);