feat(actions): add common issue lifecycle workflows

.github/workflows/issue-project-sync.yaml

@@ -0,0 +1,16 @@
+name: Issue Project Sync
+on:
+  issues:
+    types: [labeled]
+
+permissions:
+  issues: read
+
+jobs:
+  sync:
+    if: github.event.label.name == 'backlog'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: cloudoperators/common/workflows/issue-project-sync@main
+        with:
+          GH_TOKEN: ${{ secrets.GH_PROJECT_TOKEN }}

.github/workflows/issue-triage.yaml

@@ -0,0 +1,13 @@
+name: Issue Triage
+on:
+  issues:
+    types: [opened]
+
+permissions:
+  issues: write
+
+jobs:
+  triage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: cloudoperators/common/workflows/issue-triage@main

CONTRIBUTING.md

@@ -39,6 +39,16 @@ The following rule governs code contributions:
 
 ## Issues and Planning
 
-* We use GitHub issues to track bugs and enhancement requests.
+We follow a shared issue lifecycle across all `cloudoperators` repositories. See the **[Issue Lifecycle documentation](https://github.com/cloudoperators/common/blob/main/ISSUE_LIFECYCLE.md)** for the full process including:
 
-* Please provide as much context as possible when you open an issue. The information you provide must be comprehensive enough to reproduce that issue for the assignee.
+* Automatic triage labeling
+* Triage decision matrix
+* Definition of Ready
+* Refinement workflow
+* Sprint/quarter planning
+
+Quick links:
+
+* [Issues needing triage (org-wide)](https://github.com/issues?q=org%3Acloudoperators+label%3Aneeds-triage+is%3Aopen+sort%3Acreated-asc)
+* [Issues ready to pick up (`backlog`)](https://github.com/cloudoperators/shoot-grafter/issues?q=is%3Aopen+is%3Aissue+label%3Abacklog)
+* [Project board](https://github.com/orgs/cloudoperators/projects/9)