fix: use .versions | keys | last for deterministic latest MC version

The Fill v3 API returns .versions as an object (keys = MC version strings),
not an array. Using `keys | last` yields the lexicographically highest
(= newest) version reliably. Fixes broken `.versions | last` (was null on
object input) and the non-deterministic `keys_unsorted[0]` variant.

Author: TimInTech

setup_minecraft_lxc.sh

@@ -45,7 +45,7 @@ fi
 # ── Download latest stable PaperMC via Fill v3 API ──
 FILL_API="https://fill.papermc.io/v3/projects/paper"
 
-LATEST_VERSION=$(curl -fsSL -H "User-Agent: ${USER_AGENT}" "${FILL_API}" | jq -r '.versions | last')
+LATEST_VERSION=$(curl -fsSL -H "User-Agent: ${USER_AGENT}" "${FILL_API}" | jq -r '.versions | keys | last')
 echo "Latest Minecraft version: ${LATEST_VERSION}"
 
 BUILDS_JSON=$(curl -fsSL -H "User-Agent: ${USER_AGENT}" "${FILL_API}/versions/${LATEST_VERSION}/builds")