Microsoft 365: remove assigned licenses via Microsoft Graph

[LuD1161]

Goal: Free the paid M365 seat by removing assigned SKU(s).
Tasks:

• Research licensing (block sign-in vs remove license).

• Identify Graph API calls to remove user licenses (SKU IDs).

• Input: user_principal_name

• Steps: resolve → list assigned licenses → remove SKUs.

• Verify seat released (license assignment delta).

• Emit audit JSON (SKUs removed, correlationId).
  Acceptance:

• Dry-run mode.

• Idempotent.

• Unit tests with mocked Graph API.