[MartinRain]

Summary

Fixes #936.

This PR corrects SharePoint Online site storage metrics returned by SPO.Tenant/RenderAdminListData.

The existing normalization logic can produce missing storage usage values when SharePoint returns localized numeric formats, and significantly inflated quotas when values already expressed in bytes are incorrectly treated as MiB.

Changes

• Extend ConvertTo-SPOAdminListInt64 to support localized thousands separators, including spaces and non-breaking spaces, and integral values with trailing zero decimals.
• Prefer the byte-valued StorageQuota. field when available.
• Apply conservative unit handling when StorageQuota. is unavailable, avoiding incorrect conversions for small quotas.
• Add Pester regression tests covering actual SharePoint response formats, quota boundaries, invalid values, and fallback behavior.

Examples

Raw SharePoint value	Expected result
68 478 349 774	68,478,349,774 bytes
68478349774.0000	68,478,349,774 bytes
524288000.000000	500 MiB
1048576000.00000	1,000 MiB
17716740096.0000	16.5 GiB
27487790694400.0	25 TiB

Previously, a 500 MiB quota could incorrectly be reported as 500 TiB.

Validation

• Reproduced and validated against actual SharePoint admin responses across multiple independent Microsoft 365 tenants.
• Broad multi-tenant before-and-after comparison confirmed recovery of all previously missing storage usage values.
• No new missing storage values or changes to the site population were observed.
• Verified correct normalization of small and large quotas.
• Added Pester regression tests for localized values, dotted-field precedence, and fallback scenarios.

Performance and scope

• No additional Microsoft Graph or SharePoint API requests.
• No per-site enrichment calls.
• No changes to caching, scheduling, or frontend behavior.
• No permanent diagnostic logging.
• Limited to two backend PowerShell files and one Pester test file.

The fix preserves the existing SharePoint data retrieval flow while improving normalization accuracy.

Related issue: #936