chore(testing): add unit tests and update core render/network pipelines

- add new tests:
  - test_blp_loader.cpp
  - test_dbc_loader.cpp
  - test_entity.cpp
  - test_frustum.cpp
  - test_m2_structs.cpp
  - test_opcode_table.cpp
  - test_packet.cpp
  - test_srp.cpp
  - CMakeLists.txt
- add docs and progress tracking:
  - TESTING.md
  - perf_baseline.md
- update project config/build:
  - .gitignore
  - CMakeLists.txt
  - test.sh
- core engine updates:
  - application.cpp
  - game_handler.cpp
  - world_socket.cpp
  - adt_loader.cpp
  - asset_manager.cpp
  - m2_renderer.cpp
  - post_process_pipeline.cpp
  - renderer.cpp
  - terrain_manager.cpp
  - game_screen.cpp
- add profiler header:
  - profiler.hpp

include/core/profiler.hpp

@@ -0,0 +1,19 @@
+// Thin wrapper around Tracy profiler.
+// When TRACY_ENABLE is not defined, all macros expand to nothing (zero overhead).
+#pragma once
+
+#ifdef TRACY_ENABLE
+#include <tracy/Tracy.hpp>
+#else
+// No-op replacements when Tracy is disabled.
+#define ZoneScoped
+#define ZoneScopedN(x)
+#define ZoneScopedC(x)
+#define ZoneScopedNC(x, y)
+#define FrameMark
+#define FrameMarkNamed(x)
+#define FrameMarkStart(x)
+#define FrameMarkEnd(x)
+#define TracyPlot(x, y)
+#define TracyMessageL(x)
+#endif