Soft-delete an egress template by ID

Marks an egress template as inactive by setting its status to inactive. The record is not removed from the data store and remains retrievable via GET /api/v1/egress-templates/{templateId} and GET /api/v1/egress-templates (when filtering by status=inactive). No GCS files are deleted.

When to use: call this to retire a template from active use without permanently destroying its configuration or mapping history.

Preconditions: tenant-id header must be present. The template must belong to the requesting tenant; cross-tenant access returns 404 (not 403). If an export driven by this template is currently in progress, the request is rejected until that export completes.

Idempotency: calling delete again on an already-inactive template succeeds and is a no-op — version is not incremented by this operation, on first or subsequent calls.

Side effects: only the template's status field is updated. GCS files are untouched.

Returns: 204 No Content on success, with no response body.