fix: bump version to 1.3.1, remove LevelDB LOCK files from git

.gitignore

@@ -15,6 +15,9 @@ dist/
 *.lock
 .fvtt-*/
 
+# LevelDB lock files — created at runtime, must not be shipped in the zip
+**/LOCK
+
 # Compiled / minified outputs (keep source only)
 *.min.js
 *.min.css

system.json

@@ -2,7 +2,7 @@
   "id": "zero-engine",
   "title": "Zero Engine (SLA Industries)",
   "description": "A basic game system for SLA Industries using the Zero Engine rules.",
-  "version": "1.3.0-dev",
+  "version": "1.3.1",
   "compatibility": {
     "minimum": 13,
     "verified": "14.359"