[BUG] `hasLookupFunction() ` does not detect lookup usage inside helper templates (define blocks)

[susesamu]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

Fleet currently fails to detect Helm lookup usage when the lookup call is located inside helper templates defined in _helpers.tpl.
This causes charts that rely on helper-based lookup logic (such as gha-runner-scale-set) to fail when deployed through Fleet, even though they succeed with native Helm CLI.
The issue appears to be in hasLookupFunction() only inspecting t.Tree.Root and not traversing all parsed templates returned by t.Templates().

Expected Behavior

Fleet should detect lookup usage regardless of whether the function appears directly in a manifest template, inside a define block / _helpers.tpl or helper templates referenced through include/template.

Steps To Reproduce

A minimal reproducer:

_helpers.tpl

{{- define "mychart.lookupHelper" -}}
{{ lookup "v1" "Service" "default" "kubernetes" }}
{{- end -}}

configmap.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: test
data:
  value: {{ include "mychart.lookupHelper" . }}

Expected:

hasLookupFunction(chart) == true

Actual:

hasLookupFunction(chart) == false

Environment

- Architecture:
- Fleet Version:
- Cluster:
  - Provider:
  - Options:
  - Kubernetes Version:

Logs

Anything else?

No response

[sbulage]

System Information

Rancher Version	Fleet Version
v2.15-fab1af47577c3a5b41f730c9aa19debd6ce346e6-head	110.0.0+up0.16.0-alpha.10

Verification

• Created custom chart which installs configmap
• It also has _helper.tpl which fetches Service information in the configmap.
• After creating GitRepo, Fleet properly scan all template files, allowing the lookup function to run and pull live cluster data.
• Verified that it updates the data from helper funtion. (See below screenshot for more information).

Screenshot showing configmap with data fetch using helper function