Prepare Pack & Sort 0.8.8 Workshop release

[dbilici]

What changed

• Bumped Pack & Sort to 0.8.8 for the next Friends Only Workshop refresh.
• Added PACK_SORT_DEBUG() for protocol, layout, slot, action, hotkey, and debug-mode status.
• Aligned missing-value fallbacks with the defaults shown in the configuration screen.
• Expanded configuration, troubleshooting, compatibility, and release documentation.
• Included the final 0.8.7 drag/drop reliability source that was missing from the downloaded Workshop copy.

Why

The subscribed Workshop copy was older than the final drag/drop source, and fallback defaults could diverge from the Mods screen when configuration values were absent.

User impact

Normal configured worlds keep their existing values. Fresh/missing configuration now falls back consistently to F7/F8, disabled standalone bag/Quick Stack hotkeys, and Quick Stack disabled by default.

Validation

• All packaged Lua sources passed syntax parsing.
• DST API 10 metadata, mod icon files, static assets, 512×512 preview, and checksums passed.
• The existing sorting regression suite had passed on the preceding 0.8.7 sorting code; 0.8.8 changes diagnostics and configuration fallback handling.
• No development/log/OS files are included.
• git diff --check passed.