Rewrite e2e tests in Go, replace bash-in-YAML test steps

Move all e2e test logic from bash steps in ci.yaml into Go test files
under test/e2e/. CI now sets up infrastructure (KinD, Knative, CRDs,
controllers, Gitea) then runs `go test -tags=e2e ./test/e2e/`.

Benefits:
- Tests run concurrently via t.Parallel()
- No more bash-in-YAML maintenance burden
- Each test creates its own isolated resources with cleanup
- Proper Go test output with -v
- Build-tagged so `go test ./...` skips them

Tests:
- TestPushTransaction: push main to a new branch, verify on git server
- TestPushTransactionMultipleRefSpecs: push to two branches at once
- TestRepoSync: create two repos, set up GitRepoSync, verify controller

https://claude.ai/code/session_01QfFzqKQUsxxBsiZUhuJ3pG

test/e2e/sync_test.go

@@ -0,0 +1,77 @@
+//go:build e2e
+
+package e2e
+
+import (
+	"context"
+	"testing"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	gitv1alpha1 "github.com/imjasonh/git-k8s/pkg/apis/git/v1alpha1"
+)
+
+func TestRepoSync(t *testing.T) {
+	t.Parallel()
+
+	// Create two repos on Gitea.
+	createGiteaRepo(t, "e2e-sync-a")
+	createGiteaRepo(t, "e2e-sync-b")
+
+	secretName := createCredentialsSecret(t, "e2e-sync-creds")
+	createGitRepository(t, "e2e-sync-repo-a", "e2e-sync-a", secretName)
+	createGitRepository(t, "e2e-sync-repo-b", "e2e-sync-b", secretName)
+
+	// Create GitBranch CRs and populate their headCommit via the push controller.
+	// First, push main to itself to get the push controller to set headCommit.
+	branchA := createGitBranch(t, "e2e-sync-branch-a", "e2e-sync-repo-a", "main")
+	branchB := createGitBranch(t, "e2e-sync-branch-b", "e2e-sync-repo-b", "main")
+
+	// We need headCommit set on both branches for the sync controller.
+	// Patch them with the actual commit from Gitea.
+	commitA := getGiteaBranchCommit(t, "e2e-sync-a", "main")
+	commitB := getGiteaBranchCommit(t, "e2e-sync-b", "main")
+	t.Logf("Repo A main commit: %s", commitA)
+	t.Logf("Repo B main commit: %s", commitB)
+
+	ctx := context.Background()
+	branchA.Status.HeadCommit = commitA
+	if _, err := gitClient.GitBranches(testNamespace).UpdateStatus(ctx, branchA, metav1.UpdateOptions{}); err != nil {
+		t.Fatalf("updating branch A status: %v", err)
+	}
+	branchB.Status.HeadCommit = commitB
+	if _, err := gitClient.GitBranches(testNamespace).UpdateStatus(ctx, branchB, metav1.UpdateOptions{}); err != nil {
+		t.Fatalf("updating branch B status: %v", err)
+	}
+
+	// Create a GitRepoSync between the two repos.
+	syncObj := &gitv1alpha1.GitRepoSync{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "e2e-sync",
+			Namespace: testNamespace,
+		},
+		Spec: gitv1alpha1.GitRepoSyncSpec{
+			RepoA:      gitv1alpha1.SyncRepoRef{Name: "e2e-sync-repo-a"},
+			RepoB:      gitv1alpha1.SyncRepoRef{Name: "e2e-sync-repo-b"},
+			BranchName: "main",
+		},
+	}
+	_, err := gitClient.GitRepoSyncs(testNamespace).Create(ctx, syncObj, metav1.CreateOptions{})
+	if err != nil {
+		t.Fatalf("creating GitRepoSync: %v", err)
+	}
+	t.Cleanup(func() {
+		gitClient.GitRepoSyncs(testNamespace).Delete(ctx, "e2e-sync", metav1.DeleteOptions{})
+	})
+
+	// Wait for the sync controller to set a phase.
+	result := waitForSyncPhase(t, "e2e-sync")
+	t.Logf("GitRepoSync phase: %s, message: %s", result.Status.Phase, result.Status.Message)
+
+	// The sync controller should have processed this.
+	// Since both repos are different auto_init repos, commits differ,
+	// so we expect Conflicted (no common ancestor) or another non-empty phase.
+	if result.Status.Phase == "" {
+		t.Fatal("sync controller did not set a phase")
+	}
+}