Switch to Buildah for container builds (#51)

## Summary
- Replace Docker with Buildah for container image builds
- No Docker socket required - buildah is daemonless
- Cleaner security model (no privileged containers or socket mounting)
- Remove Docker-related security context from deployment

## Changes
- Update Dockerfile to install buildah/podman instead of docker-cli
- Configure buildah storage with overlay driver and fuse-overlayfs
- Update composite action to use `buildah bud` and `buildah push`
- Add `imagePullPolicy: Always` to ensure fresh image pulls
- Update test workflow to verify buildah/podman

## Testing
- [ ] Runner pod starts successfully
- [ ] Buildah is available in runner
- [ ] Test workflow verifies buildah/podman versions
- [ ] Container build workflow builds and pushes to zot

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: https://forge.tail8d86e.ts.net/eblume/blumeops/pulls/51

mise-tasks/container-list

@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+#MISE description="List available containers and their recent tags"
+
+set -euo pipefail
+
+REGISTRY="registry.tail8d86e.ts.net"
+WORKFLOW_DIR=".forgejo/workflows"
+
+echo "Container Images"
+echo "================"
+echo ""
+
+# Find all build-*.yaml workflows
+for workflow in "$WORKFLOW_DIR"/build-*.yaml; do
+    [[ -f "$workflow" ]] || continue
+
+    # Extract container name from filename: build-runner.yaml -> runner
+    filename=$(basename "$workflow")
+    container="${filename#build-}"
+    container="${container%.yaml}"
+
+    # Skip if not a container build workflow (check for image_name)
+    if ! grep -q "image_name:" "$workflow" 2>/dev/null; then
+        continue
+    fi
+
+    # Extract image name from workflow
+    image=$(grep -E "^\s+image_name:" "$workflow" | head -1 | awk '{print $2}')
+
+    echo "📦 $container"
+    echo "   Image: $REGISTRY/$image"
+    echo "   Workflow: $workflow"
+
+    # Query zot for recent tags
+    tags=$(curl -sf "https://$REGISTRY/v2/$image/tags/list" 2>/dev/null | jq -r '.tags // [] | .[]' | grep -E '^v[0-9]' | sort -V | tail -4 || true)
+
+    if [[ -n "$tags" ]]; then
+        echo "   Recent tags:"
+        echo "$tags" | while read -r tag; do
+            echo "     - $tag"
+        done
+    else
+        echo "   Recent tags: (none)"
+    fi
+    echo ""
+done
+
+echo "---"
+echo "To release a new version:"
+echo "  mise run container-release <container> <version>"
+echo ""
+echo "Example:"
+echo "  mise run container-release runner v1.0.0"

mise-tasks/container-release

@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+#MISE description="Release a container image by creating a git tag"
+
+set -euo pipefail
+
+CONTAINER="${1:-}"
+VERSION="${2:-}"
+
+if [[ -z "$CONTAINER" || -z "$VERSION" ]]; then
+    echo "Usage: mise run container-release <container> <version>"
+    echo ""
+    echo "Run 'mise run container-list' to see available containers and recent tags."
+    exit 1
+fi
+
+# Validate version format
+if [[ ! "$VERSION" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+    echo "Error: Version must be in format vX.Y.Z (e.g. v1.0.0)"
+    exit 1
+fi
+
+TAG="${CONTAINER}-${VERSION}"
+
+echo "Creating release tag: $TAG"
+echo ""
+
+# Check if tag already exists
+if git rev-parse "$TAG" >/dev/null 2>&1; then
+    echo "Error: Tag '$TAG' already exists"
+    echo "Existing tags for $CONTAINER:"
+    git tag -l "${CONTAINER}-v*" | sort -V | tail -5
+    exit 1
+fi
+
+# Find the workflow file to determine image name
+WORKFLOW_FILE=".forgejo/workflows/build-${CONTAINER}.yaml"
+if [[ ! -f "$WORKFLOW_FILE" ]]; then
+    echo "Error: No workflow found for container '$CONTAINER'"
+    echo ""
+    echo "Run 'mise run container-list' to see available containers."
+    exit 1
+fi
+
+# Extract image name from workflow
+IMAGE=$(grep -E "^\s+image_name:" "$WORKFLOW_FILE" | head -1 | awk '{print $2}')
+if [[ -z "$IMAGE" ]]; then
+    echo "Error: Could not determine image name from $WORKFLOW_FILE"
+    exit 1
+fi
+
+echo "Container: $CONTAINER"
+echo "Workflow: $WORKFLOW_FILE"
+echo "Image: registry.tail8d86e.ts.net/$IMAGE:$VERSION"
+echo ""
+
+# Confirm
+read -p "Create tag and push? [y/N] " -n 1 -r
+echo
+if [[ ! $REPLY =~ ^[Yy]$ ]]; then
+    echo "Aborted."
+    exit 0
+fi
+
+# Create and push tag
+git tag "$TAG"
+git push origin "$TAG"
+
+echo ""
+echo "✅ Tag '$TAG' created and pushed"
+echo ""
+echo "The workflow will now build and push:"
+echo "  registry.tail8d86e.ts.net/$IMAGE:$VERSION"
+echo ""
+echo "Monitor the build at:"
+echo "  https://forge.tail8d86e.ts.net/eblume/blumeops/actions"