refactor(ci): improve workflow portability and remove redundant steps

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

.github/WORKFLOWS.md

@@ -279,7 +279,7 @@ Some workflows require repository secrets:
 
 You can view the status of all workflows:
 
-- **Actions tab:** https://github.com/objectstack-ai/objectos/actions
+- **Actions tab:** [View workflows](../../actions)
 - **Badge:** Add workflow badges to README for quick status overview
 
 ---

.github/workflows/greetings.yml

@@ -23,13 +23,13 @@ jobs:
             Please make sure you've provided all the necessary information and context.
             Our team will review this as soon as possible.
             
-            In the meantime, you might want to check out our [Contributing Guide](https://github.com/objectstack-ai/objectos/blob/main/CONTRIBUTING.md)
+            In the meantime, you might want to check out our [Contributing Guide](https://github.com/${{ github.repository }}/blob/main/CONTRIBUTING.md)
             and [Documentation](https://objectos.org/docs).
           pr-message: >
             🎉 Thanks for opening your first pull request! We're excited to review your contribution.
             
             Please make sure:
-            - [ ] Your code follows our [coding standards](https://github.com/objectstack-ai/objectos/blob/main/CONTRIBUTING.md)
+            - [ ] Your code follows our [coding standards](https://github.com/${{ github.repository }}/blob/main/CONTRIBUTING.md)
             - [ ] All tests pass
             - [ ] You've added tests for new features
             - [ ] Documentation is updated (if needed)

.github/workflows/pr-size.yml

@@ -12,10 +12,6 @@ jobs:
       pull-requests: write
 
     steps:
-      - name: Label PR by size
-        uses: actions/labeler@v5
-        continue-on-error: true
-        
       - name: Calculate PR size
         id: pr-size
         uses: actions/github-script@v7