Quest NPCs turn blue and stop facing the hero once their quest is done

A dialog's quest comes from the game's script labels ("Dialog:<name>",
quest at +0x48). When that quest is done and not in progress, IsQuestNpc
answers false (blue on the minimap) and the idle action's type check
skips the turn towards the hero.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -78,6 +78,7 @@ add_library(sacredK SHARED
     src/mods/mapreveal.cpp
     src/mods/questbook.cpp
     src/mods/questfail.cpp
+    src/mods/questnpc.cpp
     src/mods/anticheat.cpp
     src/mods/loadingscreen.cpp
 )