feat: ocean (#16)

* feat(gameplay): add Ocean biome with water generation and heightmap adjustments

- Introduce Ocean biome enum, builder, and detection logic.
- Add ocean water building to all existing biomes and modify heightmap thresholds for low mountainous areas.
- Skip cave and river generation in Ocean (and River) biomes; avoid carving water blocks.
- Comment out border blending call and update block fill logic.

* fix(gameplay): re-enable border blending and protect water in cave gen

* refactor(generation): move ocean water build to later phase

* feat(block): add is_transitional property and refine border blending

* fix(block): set stone block as transitional

* fix(world): generate temporary chunks for surface blend neighbor data

* fix(gameplay): simplify block fill logic in blend_surface_blocks_borders

* refactor(tree): remove debug logging and unused include

src/gameplay/chunk.cpp

@@ -199,9 +199,8 @@ void Chunk::gen_phase_six(
         Logger::error("ChunkGenerator is Nullptr");
         return;
     }
+    // This must be fully completed before any other operations can proceed!
     m_generator->blend_surface_blocks_borders(neighbor_block);
-    m_generator->generate_cave();
-    m_generator->generate_river();
 }
 
 void Chunk::gen_phase_seven() {
@@ -209,6 +208,10 @@ void Chunk::gen_phase_seven() {
         Logger::error("ChunkGenerator is Nullptr");
         return;
     }
+    m_generator->ocean_build();
+    m_generator->generate_river();
+    m_generator->generate_cave();
+
     m_generator->generate_vegetation();
     mark_dirty();
     m_generator = nullptr;