Update .wav samples to use 'agbl' chunk to accomodate for vanilla's off-by-one loop end behavior (#712)

tools/wav2agb/wav_file.h

@@ -8,6 +8,16 @@
 
 #define WAV_INVALID_VAL 0xFFFFFFFFu
 
+// Structure for WAV chunk utilities
+struct WavChunk {
+    std::string id;
+    std::vector<uint8_t> data;
+};
+
+void write_wav_with_agbl_chunk(const std::string& output_path,
+                                std::vector<WavChunk>& chunks,
+                                uint32_t loop_end_value);
+
 class wav_file {
 public:
     wav_file(const std::string& path);
@@ -34,5 +44,8 @@ public:
     double tuning = 0.0;    // cents
     uint8_t midiKey = 60;
     uint32_t sampleRate;
+    uint32_t numSamples = 0; // total number of samples in the file
     uint32_t agbPitch = 0; // optional: exact GBA pitch value from 'agbp' chunk (0 = not present)
+    uint32_t agbLoopEnd = 0; // optional: exact loop end from 'agbl' chunk (0 = not present)
+    std::vector<WavChunk> chunks; // raw chunks from the WAV file (for re-writing with modifications)
 };