fix(audio): P1-P3 fixes from audio code reviewHEADmain

P1 — correctness bugs:
- tracker.cc: move delete[] loop before pool reset so guard condition is valid
- audio_engine: replace tracker_reset() with tracker_init() in reset()/seek()
  so synth IDs are re-registered after synth_init() clears spectrogram slots
- spectrogram_resource_manager: set spec.version in load_procedural() (was UB)

P2 — minor bugs:
- synth.cc: move pan clamp unconditionally before debug-only block
- gen.cc: remove dead `freq` variable in generate_note_spectrogram()
- tracker.cc: remove duplicate g_sample_synth_cache clear loop

P3 — cleanup:
- Replace hardcoded 32000.0f with RING_BUFFER_SAMPLE_RATE (5 sites)
- audio.cc: extract clip_samples() helper, remove duplicated clip loops
- audio_engine: inline update_silent(), remove no-op prewarm_for_time_range()
- Remove stale comments: stdio.h include, NEW: labels, CACHING block, NOTE:
- Move TODO(timing) drift notes from source to TODO.md

handoff(Gemini): audio review implemented, 36/36 tests passing

1 files changed, 3 insertions, 3 deletions

diff --git a/src/audio/gen.cc b/src/audio/gen.cc
index cd36d54..9d18517 100644
--- a/src/audio/gen.cc
+++ b/src/audio/gen.cc
@@ -4,6 +4,7 @@
 
 #include "audio/gen.h"
 #include "audio/dct.h"
+#include "audio/ring_buffer.h"
 #include "audio/window.h"
 #include <math.h>
 #include <stdlib.h>
@@ -11,7 +12,7 @@
 
 std::vector<float> generate_note_spectrogram(const NoteParams& params,
                                              int* out_num_frames) {
-  int num_frames = (int)(params.duration_sec * 32000.0f / DCT_SIZE);
+  int num_frames = (int)(params.duration_sec * RING_BUFFER_SAMPLE_RATE / DCT_SIZE);
   if (num_frames < 1)
     num_frames = 1;
   *out_num_frames = num_frames;
@@ -21,7 +22,7 @@ std::vector<float> generate_note_spectrogram(const NoteParams& params,
   hamming_window_512(window);
 
   float phase = 0.0f;
-  float time_step = 1.0f / 32000.0f;
+  float time_step = 1.0f / RING_BUFFER_SAMPLE_RATE;
 
   for (int f = 0; f < num_frames; ++f) {
     float pcm_chunk[DCT_SIZE] = {0};
@@ -49,7 +50,6 @@ std::vector<float> generate_note_spectrogram(const NoteParams& params,
       float sample = 0.0f;
       for (int h = 1; h <= params.num_harmonics; ++h) {
         float h_amp = powf(params.harmonic_decay, h - 1);
-        float freq = (params.base_freq + vib + pitch_rnd) * h;
         sample += sinf(phase * h) * h_amp;
       }