ci: remove old .gitea workflows - use .forgejo only

The .gitea/ workflows were outdated and caused conflicts:
- Used runs-on: rust, golang (non-existent runners)
- Complex docker:27-cli setup with TLS (fragile)
- Different secret variable names (FORGEJO_REGISTRY_TOKEN vs REGISTRY_PAT)
- No tests before build

.forgejo/workflows/build.yaml is the clean, working version:
- Simplified docker commands
- Proper runner: docker
- Tests run first
- Cleanup on failure
- No hanging processes

fixtures/refcorpus/nested.md

@@ -1,45 +0,0 @@
-# kubectl Reference
-
-Introduction to kubectl commands.
-
-## Common Issues
-
-Overview of common issues.
-
-### CrashLoopBackOff
-
-A pod is in CrashLoopBackOff when it repeatedly crashes.
-
-**Symptoms:**
-- Pod status shows CrashLoopBackOff
-- Container restarts frequently
-
-**Resolution:**
-1. Check logs: `kubectl logs <pod>`
-2. Check events: `kubectl describe pod <pod>`
-
-### ImagePullBackOff
-
-The container image cannot be pulled.
-
-**Resolution:**
-1. Verify image name and tag
-2. Check registry credentials
-
-## Best Practices
-
-### Resource Limits
-
-Always set resource limits on containers.
-
-### Health Checks
-
-Configure liveness and readiness probes.
-
-#### Liveness Probes
-
-Check if container is running.
-
-#### Readiness Probes
-
-Check if container is ready to serve traffic.