Summary

Implements cross-platform time detection to make Project-AI-MemoryCore universally accessible across all operating systems and shell environments. Addresses #2.

Changes:

• Added cascading detection strategy to time-aware-core.md: tries bash date first, then PowerShell Get-Date, then CMD time /T, with a graceful fallback
• Added platform compatibility matrix covering Linux, macOS, Windows (Git Bash/MSYS2, WSL, PowerShell, CMD)
• Added "commands to avoid" section to prevent common cross-platform pitfalls (e.g., bare date on Windows CMD triggers interactive date setter)
• Updated Save-Diary-System install protocol and SKILL.md to reference cross-platform commands instead of platform-specific ones
• Updated Time-based-Aware-System README with universal accessibility claims and detection table

Files modified (4):

• Feature/Time-based-Aware-System/time-aware-core.md -- core detection strategy + compatibility matrix
• Feature/Time-based-Aware-System/README.md -- cross-platform detection table + universal accessibility
• Feature/Save-Diary-System/install-save-diary.md -- replaced Get-Date-only fallback
• Feature/Save-Diary-System/SKILL.md -- updated timestamp rule

Tested on

• Windows 11 + Git Bash (MSYS2) -- date +"%H:%M" works (MSYS2 bundles GNU date)
• Windows 11 + PowerShell -- Get-Date -Format "HH:mm" works
• Production AI companion system running daily on Windows with Claude Code CLI

Notes

• This PR focuses on the Time-based Aware System and Save Diary System, which are the two features that directly reference time detection commands
• The LRU Project Management and Auto-Commit systems use generic "current date/time" references (no platform-specific commands) so they don't need changes
• Backward compatible -- no breaking changes to existing behavior