feat(plugin/ui5-modernization): add UI5 Modernization plugin

Add the SAP UI5 Modernization plugin (SAP SE / github.com/UI5) to the
official marketplace. Sibling of the already-listed ui5 and
ui5-typescript-conversion plugins from the same repo.

Onboarded on behalf of the developer (Florian Vogt, SAP): the original
contribution PR #3298 was auto-closed by the external-contributor gate,
and SAP cannot currently use the submission form.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -3025,6 +3025,24 @@
       },
       "homepage": "https://github.com/UI5/plugins-coding-agents"
     },
+    {
+      "name": "ui5-modernization",
+      "description": "Complete UI5 modernization toolkit with workflow and specialized fix patterns for modernizing SAPUI5/OpenUI5 applications.",
+      "author": {
+        "name": "SAP SE",
+        "email": "openui5@sap.com",
+        "url": "https://www.sap.com"
+      },
+      "category": "development",
+      "source": {
+        "source": "git-subdir",
+        "url": "https://github.com/UI5/plugins-coding-agents.git",
+        "path": "plugins/ui5-modernization",
+        "ref": "main",
+        "sha": "1d4dedd56afcd1c3269c4d80f09e2ddb7f1bf5be"
+      },
+      "homepage": "https://github.com/UI5/plugins-coding-agents"
+    },
     {
       "name": "ui5-typescript-conversion",
       "description": "SAPUI5 / OpenUI5 plugin for coding agents. Convert JavaScript based UI5 projects to TypeScript.",