refactor: terrain generation (#9)

* feat: add BlockType

* refactor: use fBM for heightmap generation

* feat: improve mountain realism

* refactor: adjust mountain spawn probability

* feat: add biome boundary blending

* refactor: remove resolve_biome_adjacency_conflict function

* feat: add snowy plain

* perf: speed up world generation

* refactor: lower overall terrain height

include/Cubed/gameplay/builders/snowy_plain_builder.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "Cubed/gameplay/builders/biome_builder.hpp"
+namespace Cubed {
+
+class ChunkGenerator;
+
+class SnowyPlainBuilder : public BiomeBuilder {
+public:
+    SnowyPlainBuilder(ChunkGenerator& chunk_generator);
+    void build_biome() override;
+    ChunkGenerator& get_chunk_generator() override;
+    void build_vegetation() override;
+
+private:
+    ChunkGenerator& m_chunk_generator;
+
+    void build_blocks();
+};
+
+} // namespace Cubed