[Issue] ARM child resource endpoints for agent sub-resources are inaccessible

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ARM child resource endpoints for agent sub-resources (tools, skills, scheduledTasks, incidentFilters) are inaccessible for external (non-Microsoft-internal) tenants.

When running the `sreagent-templates/bin/export-agent.sh` script does not export a couple of things any longer.

Noted that the original scripts used `2025-05-01-preview`, but that version now returns a completely different error: "Agent Extensions is invalid. Agent Extensions are not available for this tenant. This feature is restricted to internal tenants only."

After i locally switched to `2026-01-01`, the child endpoints return "Unsupported API version".

So both versions are broken for these child resources, in different ways. The `2026-01-01` bump wouldn't cause the breakage either, the ARM child resource path for tools/skills/scheduledTasks/incidentFilters has become inaccessible for external tenants entirely.

Start with sreagent-templates/bin/export-agent.sh and trace the child-resource requests for tools, skills, scheduledTasks, and incidentFilters. Compare the 2025-05-01-preview and 2026-01-01 responses for external tenants; done means the script can export those sub-resources through a supported endpoint and API version.

Written by the indexing model from the issue text.