chore: add pushLDBtoYML/pullYMLtoLDB scripts, gitignore packs_src

.gitignore

@@ -17,3 +17,6 @@ packs-system/**/CURRENT
 packs-system/**/LOCK
 packs-system/**/MANIFEST-*
 
+# YAML source for pack round-trip
+packs_src/
+

tools/pullYMLtoLDB.mjs

@@ -0,0 +1,2 @@
+import { CompendiumsManager } from './CompendiumsManager.mjs';
+CompendiumsManager.packToDistDir('packs_src', 'packs-system');

tools/pushLDBtoYML.mjs

@@ -0,0 +1,2 @@
+import { CompendiumsManager } from './CompendiumsManager.mjs';
+CompendiumsManager.unpackToSrcDir('packs_src', 'packs-system');