add config refactor structure

src/core/Config.h

@@ -0,0 +1,33 @@
+#pragma once
+#include <string>
+
+struct AquariumConfig {
+  // Entity spawn settings
+  int initial_fish_count = -1;    // -1 means auto-calculate
+  int initial_seaweed_count = -1; // -1 means auto-calculate
+  int max_bubbles = 50;
+
+  // Animation settings
+  int frame_delay_ms = 100;
+  bool enable_big_entities = true;
+  bool enable_bubbles = true;
+
+  // Visual settings
+  bool use_colors = true;
+  bool use_bold = true;
+
+  // Spawn rates (lower = more frequent)
+  int fish_bubble_rate = 10;        // 1 in N chance per frame
+  int big_entity_spawn_delay = 100; // frames between big entities
+
+  // Performance settings
+  bool optimize_rendering = true;
+  int max_entities = 200;
+
+  // Debug settings
+  bool show_fps = false;
+  bool show_entity_count = false;
+  bool debug_mode = false;
+};
+
+extern AquariumConfig g_config;