feat: Implement spectool & specview; refactor coding style; update docs

This commit introduces new tools for spectrogram manipulation and visualization, establishes a consistent coding style, and updates project documentation.

Key changes include:

- **Spectrogram Tools:

  - : A command-line utility for analyzing WAV/MP3 files into custom  spectrogram format and playing back these spectrograms via the synth engine.

  - : A command-line tool for visualizing  spectrogram files as ASCII art in the console.

- **Coding Style Enforcement:

  - Added a  configuration file enforcing LLVM-based style with 2-space indentation, no tabs, and an 80-column line limit.

  - Renamed all C++ source files from  to  for project consistency.

  - Applied automatic formatting using
exit across the entire codebase.

- **Documentation & Workflow:

  - Created  to define a commit policy requiring tests to pass before committing.

  - Updated  with instructions for building and using  and , and referenced .

  - Updated  and  to reflect the new tools, audio architecture decisions (real-time additive synthesis, double-buffering for dynamic updates, WAV/MP3 support), coding style, and development workflow.

- **Build System:

  - Modified  to:

    - Include new targets for  and  under the  option.

    - Update source file extensions to .

    - Add a new end-to-end test for  to the  suite.

1 files changed, 107 insertions, 0 deletions

diff --git a/src/tests/test_synth.cc b/src/tests/test_synth.cc
new file mode 100644
index 0000000..3492057
--- /dev/null
+++ b/src/tests/test_synth.cc
@@ -0,0 +1,107 @@
+#include "audio/synth.h"
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+
+// A simple floating point comparison with a tolerance
+bool is_close(float a, float b, float epsilon = 1e-6f) {
+  return fabsf(a - b) < epsilon;
+}
+
+void test_registration() {
+  synth_init();
+  printf("Running test: Registration...\n");
+
+  float spec_buf_a[DCT_SIZE], spec_buf_b[DCT_SIZE];
+  Spectrogram spec = {spec_buf_a, spec_buf_b, 1};
+
+  // Fill up all slots
+  for (int i = 0; i < MAX_SPECTROGRAMS; ++i) {
+    int id = synth_register_spectrogram(&spec);
+    assert(id == i);
+  }
+
+  // Next one should fail
+  int fail_id = synth_register_spectrogram(&spec);
+  assert(fail_id == -1);
+
+  // Unregister one
+  synth_unregister_spectrogram(5);
+
+  // Now we should be able to register again in the freed slot
+  int new_id = synth_register_spectrogram(&spec);
+  assert(new_id == 5);
+
+  printf("...Registration test PASSED.\n");
+}
+
+void test_render() {
+  synth_init();
+  printf("Running test: Render...\n");
+
+  float spec_buf_a[DCT_SIZE] = {0};
+  Spectrogram spec = {spec_buf_a, nullptr, 1};
+
+  // Create a simple spectrum with one active bin
+  spec_buf_a[10] = 1.0f;
+
+  int id = synth_register_spectrogram(&spec);
+  assert(id != -1);
+
+  synth_trigger_voice(id, 1.0f, 0.0f);
+
+  float output_buffer[DCT_SIZE * 2] = {0}; // Stereo
+  synth_render(output_buffer, DCT_SIZE);
+
+  float total_energy = 0.0f;
+  for (int i = 0; i < DCT_SIZE * 2; ++i) {
+    total_energy += fabsf(output_buffer[i]);
+  }
+
+  // If we rendered a sound, the buffer should not be silent
+  assert(total_energy > 0.01f);
+
+  printf("...Render test PASSED.\n");
+}
+
+void test_update() {
+  synth_init();
+  printf("Running test: Update...\n");
+  float spec_buf_a[DCT_SIZE] = {0};
+  float spec_buf_b[DCT_SIZE] = {0};
+  Spectrogram spec = {spec_buf_a, spec_buf_b, 1};
+
+  spec_buf_a[10] = 1.0f; // Original sound
+  spec_buf_b[20] = 1.0f; // Updated sound
+
+  int id = synth_register_spectrogram(&spec);
+
+  // Begin update - should get back buffer B
+  float *back_buffer = synth_begin_update(id);
+  assert(back_buffer == spec_buf_b);
+
+  // We could modify it here, but it's already different.
+  // Let's just commit.
+  synth_commit_update(id);
+
+  // Now if we trigger a voice, it should play from buffer B.
+  // To test this, we'd need to analyze the output, which is complex.
+  // For this test, we'll just ensure the mechanism runs and we can
+  // begin an update on the *new* back buffer (A).
+  back_buffer = synth_begin_update(id);
+  assert(back_buffer == spec_buf_a);
+
+  printf("...Update test PASSED.\n");
+}
+
+int main() {
+  test_registration();
+  test_render();
+  test_update();
+
+  synth_shutdown();
+
+  printf("\nAll synth tests passed!\n");
+  return 0;
+}