Fix flux trace for HRs from OCIRepositorys

Before:
```
$ flux -n default trace pod default-podinfo-585856f49c-4jl4m
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x40 pc=0x10618da70]

goroutine 1 [running]:
main.traceHelm({0x106dd7b28, 0x14000201490}, {0x12f34c0d8, 0x14000783100}, {{0x1400071e130?, 0x1061e7795?}, {0x1400071e109?, 0x1000d9c84?}}, 0x140006a6030)
	/home/runner/work/flux2/flux2/cmd/flux/trace.go:404 +0x2f0
main.traceObject({0x106dd7b28, 0x14000201490}, {0x12f34c0d8, 0x14000783100}, 0x140006a6030)
	/home/runner/work/flux2/flux2/cmd/flux/trace.go:134 +0x11c
main.traceObjects({0x106dd7b28, 0x14000201490}, {0x12f34c0d8, 0x14000783100}, {0x140006a6040, 0x1, 0x0?})
	/home/runner/work/flux2/flux2/cmd/flux/trace.go:112 +0x74
main.traceCmdRun(0x14000592800?, {0x140003aea80, 0x2, 0x4})
	/home/runner/work/flux2/flux2/cmd/flux/trace.go:107 +0x180
github.com/spf13/cobra.(*Command).execute(0x108341980, {0x140003aea40, 0x4, 0x4})
	/home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.1/command.go:985 +0x834
github.com/spf13/cobra.(*Command).ExecuteC(0x108329280)
	/home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.1/command.go:1117 +0x344
github.com/spf13/cobra.(*Command).Execute(...)
	/home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.1/command.go:1041
main.main()
	/home/runner/work/flux2/flux2/cmd/flux/main.go:189 +0x78
```

After:

```
 $ ~/dev/flux/flux2/bin/flux -n default trace pod default-podinfo-585856f49c-4jl4m

Object:         Pod/default-podinfo-585856f49c-4jl4m
Namespace:      default
Status:         Managed by Flux
---
HelmRelease:    podinfo
Namespace:      flux-system
Target:         default
Revision:       6.8.0+2360bdf32ddc
Status:         Last reconciled at 2025-05-14 16:10:37 +0200 CEST
Message:        Helm install succeeded for release default/default-podinfo.v1 with chart podinfo@6.8.0+2360bdf32ddc
---
OCIRepository:   podinfo
Namespace:       flux-system
URL:             oci://ghcr.io/stefanprodan/charts/podinfo
Tag:             6.8.0
Revision:        6.8.0@sha256:2360bdf32ddc50c05f8e128118173343b0a012a338daf145b16e0da9c80081a4
Status:          Last reconciled at 2025-05-14 16:09:17 +0200 CEST
Message:         stored artifact for digest '6.8.0@sha256:2360bdf32ddc50c05f8e128118173343b0a012a338daf145b16e0da9c80081a4'
```

Signed-off-by: Max Jonas Werner <max@coppersoft.com>

cmd/flux/testdata/trace/deployment-hr-ocirepo.golden

@@ -0,0 +1,18 @@
+
+Object:         deployment/podinfo
+Namespace:      {{ .ns }}
+Status:         Managed by Flux
+---
+HelmRelease:    podinfo
+Namespace:      {{ .ns }}
+Revision:       6.3.5
+Status:         Last reconciled at {{ .helmReleaseLastReconcile }}
+Message:        Release reconciliation succeeded
+---
+OCIRepository:   podinfo-charts
+Namespace:       {{ .fluxns }}
+URL:             oci://ghcr.io/stefanprodan/charts/podinfo
+Tag:             6.8.0
+Revision:        sha256:dbdb109711ffb3be77504d2670dbe13c24dd63d8d7f1fb489d350e5bfe930dd3
+Status:          Last reconciled at {{ .ociRepositoryLastReconcile }}
+Message:         stored artifact for digest 'sha256:dbdb109711ffb3be77504d2670dbe13c24dd63d8d7f1fb489d350e5bfe930dd3'

cmd/flux/testdata/trace/deployment-hr-ocirepo.yaml

@@ -0,0 +1,86 @@
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: {{ .fluxns }}
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: {{ .ns }}
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app.kubernetes.io/name: podinfo
+    app.kubernetes.io/managed-by: Helm
+    helm.toolkit.fluxcd.io/name: podinfo
+    helm.toolkit.fluxcd.io/namespace: {{ .ns }}
+  name: podinfo
+  namespace: {{ .ns }}
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: podinfo
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: podinfo
+    spec:
+      containers:
+      - name: hello
+        command: [ "echo hello world" ]
+        image: busybox
+---
+apiVersion: helm.toolkit.fluxcd.io/v2
+kind: HelmRelease
+metadata:
+  name: podinfo
+  namespace: {{ .ns }}
+spec:
+  chartRef:
+    kind: OCIRepository
+    name: podinfo-charts
+    namespace: {{ .fluxns }}
+  interval: 5m
+status:
+  conditions:
+  - lastTransitionTime: "2021-07-16T15:42:20Z"
+    message: Release reconciliation succeeded
+    reason: ReconciliationSucceeded
+    status: "True"
+    type: Ready
+  lastAttemptedRevision: 6.3.5
+---
+apiVersion: source.toolkit.fluxcd.io/v1beta2
+kind: OCIRepository
+metadata:
+  labels:
+    kustomize.toolkit.fluxcd.io/name: flux-system
+    kustomize.toolkit.fluxcd.io/namespace: {{ .fluxns }}
+  name: podinfo-charts
+  namespace: {{ .fluxns }}
+spec:
+  interval: 10m0s
+  provider: generic
+  ref:
+    tag: 6.8.0
+  timeout: 60s
+  url: oci://ghcr.io/stefanprodan/charts/podinfo
+status:
+  artifact:
+    lastUpdateTime: "2022-08-10T10:07:59Z"
+    metadata:
+      org.opencontainers.image.revision: 6.1.6@sha1:450796ddb2ab6724ee1cc32a4be56da032d1cca0
+      org.opencontainers.image.source: https://github.com/stefanprodan/podinfo.git
+    path: "example"
+    revision: sha256:dbdb109711ffb3be77504d2670dbe13c24dd63d8d7f1fb489d350e5bfe930dd3
+    url: "example"
+  conditions:
+  - lastTransitionTime: "2021-07-20T00:48:16Z"
+    message: "stored artifact for digest 'sha256:dbdb109711ffb3be77504d2670dbe13c24dd63d8d7f1fb489d350e5bfe930dd3'"
+    reason: Succeed
+    status: "True"
+    type: Ready