Implements LIST `$expand` parity with GET by forwarding caller-provided, contract-allowlisted expands.
Key changes:
- Entra Admin Roles scan now requests `expand=principal` for role assignments so `principal.displayName` can render.
- `$expand` normalization/sanitization: top-level comma split (commas inside balanced parentheses preserved), trim, dedupe, allowlist exact match, caps (max 10 tokens, max 200 chars/token).
- Diagnostics when expands are removed/truncated (non-prod warning, production low-noise).
Tests:
- Adds/extends unit coverage for Graph contract sanitization, list request shaping, and the EntraAdminRolesReportService.
Spec artifacts included under `specs/112-list-expand-parity/`.
Co-authored-by: Ahmed Darrazi <ahmed.darrazi@live.de>
Reviewed-on: #136
