Add Implementation Design Proposals for human-readable Size, DateTime, and TimeSpan display

[Copilot]

Get-ChildItem displays raw byte counts for file sizes, making large values (e.g., 1298450612224) difficult to read at a glance. Per the issue, this work produces implementation design proposals only — no runtime implementation changes.

New files

• docs/design-proposals/human-readable-file-size-display.md — Full IDP for the Length column:

  • Documents current LengthString in FileSystemProvider.cs (raw .ToString())
  • Notes existing DisplayHumanReadableFileSize in Utils.cs (already used for copy/remove progress, binary-unit 1024-based)
  • Proposes three options: thousands separator (N0), human-readable units (1.18 TB), or the latter wrapped in an experimental feature
  • Recommended: Option 2 behind PSFileInfoHumanReadableSize experimental feature — mirrors precedent set by PSAnsiRenderingFileInfo
  • Covers binary vs. decimal units, offline file handling, column width, and backwards compatibility

• docs/design-proposals/human-readable-datetime-display.md — Full IDP for human-readable DateTime display:

  • Documents current file-listing timestamp formatting via LastWriteTimeString and relevant formatter locations
  • Proposes absolute-only, relative, dual-format, and experimental-feature-gated options
  • Recommended: relative formatting behind an experimental feature
  • Covers rollout plan, compatibility risks, thresholds, and open design questions

• docs/design-proposals/human-readable-timespan-display.md — Full IDP for human-readable TimeSpan display:

  • Documents current System.TimeSpan list/table/wide views in DotNetTypes_format_ps1xml.cs
  • Proposes numeric, humanized, dual-format, and experimental-feature-gated options
  • Recommended: humanized formatting behind an experimental feature
  • Covers unit/rounding rules, negative durations, test matrix, and open design questions

Additionally, the DateTime and TimeSpan proposal expansions were delivered in separate commits per PR feedback.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Implement Easier to read file lengths</issue_title>
<issue_description>As asked in - PowerShell#24011

We need to look to implement as detailed in this comment just the Size

However we will not implement anything as part of this work & only bring about an intended plan of action under an Implementation Design Proposal.

We should do so for Size, DateTime & TimeSpan as seperate proposals</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Implement Easier to read file lengths #170

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[kilasuit]

@copilot Could you also look to fill out the other 2 design proposals please & seperate each into separate commits please

[Copilot]

@copilot Could you also look to fill out the other 2 design proposals please & seperate each into separate commits please

Done. I fully expanded both remaining proposals and split them into separate commits:

• DateTime proposal: 8f67d27
• TimeSpan proposal: 64f6547