fix: WAV dump header corruption and early exit handling

- wav_dump_backend: Fix data_size double-counting channels (line 126)
- test_wav_dump: Assert on data_size validation instead of warning
- main: Add SIGINT/SIGTERM handlers to finalize WAV on Ctrl+C
- Guard signal handler code with DEMO_HEADLESS ifdef

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/src/tests/audio/test_wav_dump.cc b/src/tests/audio/test_wav_dump.cc
index eb14652..85b168d 100644
--- a/src/tests/audio/test_wav_dump.cc
+++ b/src/tests/audio/test_wav_dump.cc
@@ -134,12 +134,8 @@ void test_wav_format_matches_live_audio() {
   const uint32_t expected_min_size = expected_bytes_per_sec * 1.5;
   const uint32_t expected_max_size = expected_bytes_per_sec * 2.5;
 
-  // For now, accept if stereo format is correct (main regression test goal)
-  if (header.data_size < expected_min_size ||
-      header.data_size > expected_max_size) {
-    printf("    WARNING: Data size outside expected range\n");
-    // Don't fail on this for now - stereo format is the critical check
-  }
+  assert(header.data_size >= expected_min_size);
+  assert(header.data_size <= expected_max_size);
 
   // Verify file contains actual audio data (not all zeros)
   fseek(f, sizeof(WavHeader), SEEK_SET);