feat(ps1): auto-sort receipts into YYMM subfolders based on filename date

[ndomako10]

Summary

Add a feature to automatically move receipt files into the correct YYMM month subfolder under RECEIPTS_ROOT based on the date parsed from each filename.

Currently, the user must manually place receipts into the right folder (e.g. 2603\ for March 2026) before running a sync. A sorting step would eliminate that manual effort — drop files into an inbox folder, run the sorter, then sync.

Proposed behaviour

• Reads receipt files from a source folder (e.g. RECEIPTS_ROOT\Inbox\ or a user-supplied path)
• Parses each filename with the existing ConvertFrom-ReceiptFileName function
• Moves each file to RECEIPTS_ROOT\YYMM\ (creating the folder if it does not exist)
• Skips and warns on files that fail to parse (ParseOK = $false) — never moves an unparseable file
• Supports a -WhatIf / dry-run mode that prints what would move without touching the filesystem
• Reports a summary: N moved, M skipped (with reasons)

Design notes

• Should reuse ConvertFrom-ReceiptFileName as-is — no changes to the parser needed
• Could be implemented as:
  • A new script Scripts/Sort-Receipts.ps1 (cleaner separation, easier to test)
  • Or a -Sort switch on Sync-Receipts.ps1 that runs before the sync loop
  • A standalone script is preferred so sorting can be run independently of syncing
• A corresponding launcher Launchers/Run-SortReceipts.bat would follow the existing launcher pattern
• The inbox folder path should be configurable (parameter + Config.env variable, or default to RECEIPTS_ROOT\Inbox\)
• Pester tests should cover: correct target path derivation, skipping unparseable files, -WhatIf mode, and folder creation

Files affected

• Scripts/Sort-Receipts.ps1 — new script
• Launchers/Run-SortReceipts.bat — new launcher
• Config/Config.template.env — add INBOX_ROOT variable (optional)
• README.md, CLAUDE.md — document new script and launcher
• Tests/Sort-Receipts.Tests.ps1 — new test file (pure logic; no COM dependency)