feat: Integrate tracker system and update project context documentation

- Implemented the basic tracker system with runtime support (tracker.h, tracker.cc).
- Added a sample music track file (assets/music.track).
- Created a tracker compiler tool (tools/tracker_compiler.cc) to generate music data.
- Updated CMakeLists.txt to build the tracker compiler and integrate generated data.
- Updated GEMINI.md to reflect new file locations and project context.

1 files changed, 42 insertions, 0 deletions

diff --git a/src/audio/tracker.h b/src/audio/tracker.h
new file mode 100644
index 0000000..d97b483
--- /dev/null
+++ b/src/audio/tracker.h
@@ -0,0 +1,42 @@
+// This file is part of the 64k demo project.
+// It defines the tracker system for music composition.
+
+#pragma once
+
+#include "audio/gen.h"
+#include <cstdint>
+
+struct TrackerEvent {
+  float beat;
+  uint16_t sample_id;
+  float volume;
+  float pan;
+};
+
+struct TrackerPattern {
+  const TrackerEvent* events;
+  uint32_t num_events;
+  float num_beats;
+};
+
+struct TrackerPatternTrigger {
+  float time_sec;
+  uint16_t pattern_id;
+  // Modifiers could be added here
+};
+
+struct TrackerScore {
+  const TrackerPatternTrigger* triggers;
+  uint32_t num_triggers;
+  float bpm;
+};
+
+// Global music data generated by tracker_compiler
+extern const NoteParams g_tracker_samples[];
+extern const uint32_t g_tracker_samples_count;
+extern const TrackerPattern g_tracker_patterns[];
+extern const uint32_t g_tracker_patterns_count;
+extern const TrackerScore g_tracker_score;
+
+void tracker_init();
+void tracker_update(float time_sec);