feat(manager/helmfile): allow forward slashes in OCI chart names

Issue was described in [discussion][1].

The helmfile manager now properly handles OCI chart names that contain forward slashes.
Previously, the validation would reject chart names with slashes even for OCI repositories.
This change modifies the isValidChartName function to use different validation rules
for OCI vs non-OCI charts.

Added test coverage to verify the new behavior works correctly.

[1]: #26207

lib/modules/manager/helmfile/extract.spec.ts

@@ -363,6 +363,36 @@ describe('modules/manager/helmfile/extract', () => {
       });
     });
 
+    it('allows OCI chart names containing forward slashes', async () => {
+      const content = `
+      repositories:
+        - name: oci-repo
+          url: ghcr.io/example/oci-repo
+          oci: true
+      releases:
+        - name: nested-example
+          version: 1.2.3
+          chart: oci://ghcr.io/example/nested/path/chart
+      `;
+      const fileName = 'helmfile.yaml';
+      const result = await extractPackageFile(content, fileName, {
+        registryAliases: {
+          stable: 'https://charts.helm.sh/stable',
+        },
+      });
+      expect(result).toMatchObject({
+        datasource: 'helm',
+        deps: [
+          {
+            currentValue: '1.2.3',
+            depName: 'path/chart',
+            datasource: 'docker',
+            packageName: 'ghcr.io/example/nested/path/chart',
+          },
+        ],
+      });
+    });
+
     it('parses a chart with an oci repository with ---', async () => {
       const content = codeBlock`
       repositories:

lib/modules/manager/helmfile/extract.ts

@@ -18,8 +18,13 @@ import {
   localChartHasKustomizationsYaml,
 } from './utils';
 
-const isValidChartName = (name: string | undefined): boolean =>
-  !!name && !regEx(/[!@#$%^&*(),.?":{}/|<>A-Z]/).test(name);
+const isValidChartName = (name: string | undefined, oci: boolean): boolean {
+  if (oci) {
+    return !!name && !regEx(/[!@#$%^&*(),.?":{}|<>A-Z]/).test(name);
+  } else {
+    return !!name && !regEx(/[!@#$%^&*(),.?":{}/|<>A-Z]/).test(name);
+  }
+}
 
 function isLocalPath(possiblePath: string): boolean {
   return ['./', '../', '/'].some((localPrefix) =>
@@ -118,7 +123,7 @@ export async function extractPackageFile(
 
       // By definition on helm the chart name should be lowercase letter + number + -
       // However helmfile support templating of that field
-      if (!isValidChartName(res.depName)) {
+      if (!isValidChartName(res.depName, isOCIRegistry(dep.chart) || registryData[repoName]?.oci)) {
         res.skipReason = 'unsupported-chart-type';
       }