v1.4.0.5482-alpha — upstream sync

Three changes from the KeeperFX team, one of which needed care.

• Creatures asleep on payday now receive gold handed to them. An advance taken while a creature was in a non-salary state did not take effect until later. Upstream's fix, taken as-is.
• File enumeration and OS-version queries moved into the platform layer, continuing the rework this fork already adopted. Internal tidying.
• Kept: hidden files stay invisible to the game. Upstream's new enumeration skips only . and ..; this fork skips every hidden entry. That matters on Linux — campaigns, mods and workshop content usually arrive as archives built on macOS or Windows carrying ._name.cfg sidecars beside the real files. Without the filter the engine parses them as real campaigns, and because . sorts first the sidecar is picked ahead of the file it shadows. Carried into the new code and verified by planting sidecars: upstream's version logs Parsing campaign file "._bogus.cfg" common blocks failed, ours ignores them entirely.