Complete RCA investigation with documentation and workflow

Co-authored-by: dcasati <3240777+dcasati@users.noreply.github.com>

Author: Copilot

README-RCA.md

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+# ArgoCD Deployment Failure - Root Cause Analysis Complete
+
+## Investigation Status: ✅ COMPLETE
+
+The root cause analysis for GitHub Issue #12 (`🚨 ArgoCD Deployment Failed: 2-broken-apps`) has been completed.
+
+## Summary
+
+**Root Cause:** Invalid `apiVersion` field in Kubernetes manifest
+- **File:** `apps/broken-aks-store-all-in-one.yaml` (line 178)
+- **Error:** `apiVersion: apps/v` should be `apiVersion: apps/v1`
+- **Repository:** https://github.com/dcasati/argocd-notification-examples.git
+- **Commit:** `8cd04df204028ff78613a69fdb630625864037c6`
+
+This error was **intentionally introduced** for testing the ArgoCD notification system.
+
+## Posting the RCA to GitHub Issue
+
+The complete root cause analysis needs to be posted as a comment on Issue #12. Due to permission constraints in the automated environment, this requires manual action.
+
+### Option 1: Run the Workflow (Recommended)
+
+A GitHub Actions workflow has been created to post the RCA:
+
+```bash
+# Using GitHub CLI
+gh workflow run post-argocd-rca.yml \
+  --ref copilot/fix-argocd-deployment-issue-yet-again \
+  -f issue_number=12
+```
+
+**Or via GitHub Web UI:**
+1. Go to: https://github.com/DevExpGbb/agentic-platform-engineering/actions
+2. Click on "Post ArgoCD RCA to Issue" workflow
+3. Click "Run workflow"
+4. Select branch: `copilot/fix-argocd-deployment-issue-yet-again`
+5. Enter issue number: `12`
+6. Click "Run workflow"
+
+### Option 2: Manual Comment (Alternative)
+
+If you prefer to post manually, the complete RCA text is embedded in the workflow file:
+`.github/workflows/post-argocd-rca.yml`
+
+Copy the content from the `rcaComment` variable and post it as a comment on Issue #12.
+
+## Key Findings
+
+1. **The deployment failure is INTENTIONAL** - designed to test ArgoCD notifications
+2. **System is working correctly:**
+   - ✅ ArgoCD detected the invalid manifest
+   - ✅ Notifications were sent via webhook
+   - ✅ GitHub Actions created the issue automatically
+   - ✅ Issue contains appropriate troubleshooting information
+
+3. **Three remediation options provided:**
+   - Fix the source repository
+   - Use a different (valid) repository
+   - Accept as expected behavior for testing
+
+## Files Modified
+
+- `.github/workflows/post-argocd-rca.yml` - Workflow to post RCA to issue
+- `README-RCA.md` - This file
+
+## Investigation Complete
+
+No code changes are needed in this repository. The ArgoCD notification system is functioning as designed. The intentionally broken application successfully triggered the notification workflow and created an appropriate issue for investigation.