ci: fix OIDC-Token-Fehler bei Fork-PRs im Code-Review-Workflow

pull_request_target statt pull_request: GitHub stellt ACTIONS_ID_TOKEN_REQUEST_URL
nur im Basis-Repo-Kontext bereit. pull-requests: write ergänzt, damit die Aktion
Review-Kommentare posten kann.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/claude-code-review.yml

@@ -1,7 +1,7 @@
 name: Claude Code Review
 
 on:
-  pull_request:
+  pull_request_target:
     types: [opened, synchronize, ready_for_review, reopened]
 
 jobs:
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: read
-      pull-requests: read
+      pull-requests: write
       issues: read
       id-token: write