fix: auto-detect CharSections.dbc layout and add Blood Elf/Draenei NPC voices

CharSections.dbc has different field layouts between stock WotLK (textures
at field 4-6) and Classic/TBC/Turtle/HD-textured WotLK (VariationIndex at
field 4). Add detectCharSectionsFields() that probes field-4 values at
runtime to determine the correct layout, so both stock and modded clients
work without JSON changes.

Also add BLOODELF_MALE/FEMALE and DRAENEI_MALE/FEMALE voice types to the
NPC voice system — previously all Blood Elf and Draenei NPCs fell through
to GENERIC (random dwarf/gnome/night elf/orc mix).

include/audio/npc_voice_manager.hpp

@@ -38,6 +38,10 @@ enum class VoiceType {
     GNOME_FEMALE,
     GOBLIN_MALE,
     GOBLIN_FEMALE,
+    BLOODELF_MALE,
+    BLOODELF_FEMALE,
+    DRAENEI_MALE,
+    DRAENEI_FEMALE,
     GENERIC,  // Fallback
 };