feat: wire manifest resolution into install execution (#509)

scripts/lib/install/runtime.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const {
+  createLegacyCompatInstallPlan,
   createLegacyInstallPlan,
   createManifestInstallPlan,
 } = require('../install-executor');
@@ -23,6 +24,17 @@ function createInstallPlanFromRequest(request, options = {}) {
     });
   }
 
+  if (request.mode === 'legacy-compat') {
+    return createLegacyCompatInstallPlan({
+      target: request.target,
+      legacyLanguages: request.legacyLanguages,
+      projectRoot: options.projectRoot,
+      homeDir: options.homeDir,
+      claudeRulesDir: options.claudeRulesDir,
+      sourceRoot: options.sourceRoot,
+    });
+  }
+
   if (request.mode === 'legacy') {
     return createLegacyInstallPlan({
       target: request.target,