feat: add WAV load/save and ring buffer implementation

Co-authored-by: aider (deepseek/deepseek-reasoner) <aider@aider.chat>

src/ringbuffer.h

@@ -0,0 +1,21 @@
+#ifndef RINGBUFFER_H
+#define RINGBUFFER_H
+
+#include <stddef.h>
+#include <stdatomic.h>
+
+typedef struct {
+    atomic_size_t head;
+    atomic_size_t tail;
+    size_t        capacity;
+    float        *buf;
+} RingBuf;
+
+int  ring_init(RingBuf *r, size_t capacity);
+void ring_destroy(RingBuf *r);
+size_t ring_readable(const RingBuf *r);
+size_t ring_writeable(const RingBuf *r);
+size_t ring_write(RingBuf *r, const float *data, size_t count);
+size_t ring_read(RingBuf *r, float *data, size_t count);
+
+#endif