fix: derive rest state from PLAYER_BYTES_2 and add action bar 2 settings

XP bar rest state:
- isResting_ now set from PLAYER_BYTES_2 byte 3 bit 0 (rest state flag)
  on both CREATE and VALUES update object handlers
- playerRestedXp_ was missing from VALUES handler — now tracked there too
- Eliminates dependency on SMSG_SET_REST_START (wrong in WotLK opcodes.json)

Interface settings:
- New "Interface" tab in Settings window
- "Show Second Action Bar" toggle (default: on)
- Horizontal/vertical position offset sliders for bar 2
- Settings persisted to/from save file

include/ui/game_screen.hpp

@@ -112,6 +112,9 @@ private:
     bool pendingSeparateBags = true;
     bool pendingAutoLoot = false;
     bool pendingUseOriginalSoundtrack = true;
+    bool pendingShowActionBar2 = true;   // Show second action bar above main bar
+    float pendingActionBar2OffsetX = 0.0f;  // Horizontal offset from default center position
+    float pendingActionBar2OffsetY = 0.0f;  // Vertical offset from default (above bar 1)
     int pendingGroundClutterDensity = 100;
     int pendingAntiAliasing = 0;  // 0=Off, 1=2x, 2=4x, 3=8x
     bool pendingNormalMapping = true;   // on by default