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, 7 insertions, 6 deletions

diff --git a/src/audio/synth.cc b/src/audio/synth.cc
index 0866bda..45ced59 100644
--- a/src/audio/synth.cc
+++ b/src/audio/synth.cc
@@ -6,7 +6,6 @@
 #include "audio/dct.h"
 #include "util/debug.h"
 #include <math.h>
-#include <stdio.h>  // For printf
 #include <string.h> // For memset
 
 #if !defined(STRIP_ALL)
@@ -169,6 +168,11 @@ void synth_trigger_voice(int spectrogram_id, float volume, float pan,
     return;
   }
 
+  if (pan < -1.0f)
+    pan = -1.0f;
+  else if (pan > 1.0f)
+    pan = 1.0f;
+
 #if defined(DEBUG_LOG_SYNTH)
   // VALIDATION: Check volume and pan ranges
   if (volume < 0.0f || volume > 2.0f) {
@@ -177,9 +181,8 @@ void synth_trigger_voice(int spectrogram_id, float volume, float pan,
   }
   if (pan < -1.0f || pan > 1.0f) {
     DEBUG_SYNTH(
-        "[SYNTH WARNING] Invalid pan=%.2f (clamping) for spectrogram_id=%d\n",
+        "[SYNTH WARNING] Invalid pan=%.2f for spectrogram_id=%d\n",
         pan, spectrogram_id);
-    pan = (pan < -1.0f) ? -1.0f : 1.0f;
   }
   if (start_offset_samples < 0) {
     DEBUG_SYNTH("[SYNTH WARNING] Negative start_offset=%d, clamping to 0\n",
@@ -210,8 +213,7 @@ void synth_trigger_voice(int spectrogram_id, float volume, float pan,
         memset(v.overlap_buf, 0, sizeof(v.overlap_buf));
       v.fractional_pos =
           0.0f; // Initialize fractional position for tempo scaling
-      v.start_sample_offset =
-          start_offset_samples; // NEW: Sample-accurate timing
+      v.start_sample_offset = start_offset_samples;
       v.active_spectral_data =
           g_synth_data.active_spectrogram_data[spectrogram_id];
 
@@ -242,7 +244,6 @@ void synth_render(float* output_buffer, int num_frames) {
       if (!v.active)
         continue;
 
-      // NEW: Skip this sample if we haven't reached the trigger offset yet
       if (v.start_sample_offset > 0) {
         v.start_sample_offset--;
         continue; // Don't produce audio until offset elapsed