feat(games): add the generic d6 oracle game package

Serves as the reference implementation of the game package contract:
rules, spark tables, character backgrounds, and an example command.

games/generic/tables/complication-themes.csv

@@ -0,0 +1,7 @@
+min,max,text,tags
+1,1,"A past debt comes due",obligation
+2,2,"An ally's hidden motive surfaces",npc
+3,3,"The environment turns hostile",environment
+4,4,"A resource runs out at the worst time",resource
+5,5,"Someone else wants the same thing",rival
+6,6,"A truth is revealed that reframes the goal",revelation