chore: remove dead specplay tool and all references

specplay was removed from the build but source/docs remained.
Delete tools/specplay.cc, tools/specplay_README.md, and remove
specplay sections from TOOLS_REFERENCE.md and BACKLOG.md.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 0 insertions, 164 deletions

diff --git a/tools/specplay_README.md b/tools/specplay_README.md
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--- a/tools/specplay_README.md
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-# specplay - Audio Analysis & Playback Tool
-
-Standalone diagnostic tool for analyzing and playing .spec spectrogram files and .wav audio files.
-
-## Usage
-
-```bash
-./build/specplay <file.spec|file.wav>
-```
-
-## Features
-
-### Current (v1.0)
-- ✅ Plays .spec files via IDCT synthesis (matches demo playback exactly)
-- ✅ Plays .wav files for comparison
-- ✅ Reports PCM statistics:
-  - **Peak level**: Maximum absolute sample value (detects clipping if > 1.0)
-  - **RMS level**: Root-mean-square energy (loudness measure)
-- ✅ Real-time clipping detection during playback with sample position
-- ✅ Validates .spec file format (magic bytes, version, DCT size)
-
-### Example Output
-```
-Loading .spec: version=1, dct_size=512, frames=68
-PCM stats: Peak=0.403, RMS=0.058
-Playing 1.09 seconds... Press Ctrl+C to stop.
-Playback complete.
-```
-
-## Use Cases
-
-1. **Debugging Audio Issues**
-   - Quickly identify which samples have clipping (Peak > 1.0)
-   - Compare .wav source vs .spec output to detect analysis artifacts
-   - Verify spectrogram regeneration after DCT changes
-
-2. **Quality Assurance**
-   - Batch test all .spec files for clipping before committing
-   - Measure loudness consistency across samples (RMS levels)
-   - Validate spectrograms match expected characteristics
-
-3. **Development Workflow**
-   - Test individual samples without running full demo
-   - A/B compare different spectrogram generation parameters
-   - Verify procedural note generation output
-
-## Technical Details
-
-- **Sample Rate**: 32kHz (matches demo audio engine)
-- **Format**: Mono (duplicated to stereo for playback)
-- **IDCT**: Uses same `idct_512()` function as demo (bit-exact)
-- **Clamping**: Clipping detected but samples clamped to [-1, 1] for playback
-
-## Future Enhancement Ideas
-
-### Priority 1: Analysis Features
-- [ ] **Spectral visualization**: ASCII art frequency plot
-- [ ] **Waveform display**: Time-domain amplitude graph
-- [ ] **Frequency analysis**: Dominant frequency, spectral centroid
-- [ ] **Dynamic range**: Measure headroom, suggest normalization
-- [ ] **Duration info**: Show seconds, samples, frames
-
-### Priority 2: Comparison Tools
-- [ ] **Diff mode**: `specplay --compare file.wav file.spec`
-  - Side-by-side PCM stats
-  - RMS error, peak difference
-  - Correlation coefficient
-- [ ] **Batch mode**: `specplay --batch assets/final/*.spec`
-  - Generate CSV report of all stats
-  - Sort by peak level (find clipping candidates)
-  - Find outliers (unusually loud/quiet samples)
-
-### Priority 3: Export Features
-- [ ] **WAV export**: `specplay file.spec --export output.wav`
-  - Convert .spec → .wav for external analysis
-  - Useful for importing into audio editors
-- [ ] **Normalization**: `specplay file.spec --normalize --export normalized.wav`
-  - Auto-scale to target peak/RMS
-  - Preserve transients
-
-### Priority 4: Advanced Analysis
-- [ ] **Spectral envelope**: Extract formants, resonances
-- [ ] **Harmonic analysis**: Detect fundamental frequency, harmonics
-- [ ] **Onset detection**: Find transient attacks (kick/snare hits)
-- [ ] **Spectral flux**: Measure frequency content change over time
-
-### Priority 5: Interactive Mode
-- [ ] **Seek controls**: Play from specific time offset
-- [ ] **Loop mode**: Repeat playback indefinitely
-- [ ] **Volume control**: Adjust playback gain
-- [ ] **Real-time waveform**: Live visualization during playback
-
-## Integration with Build System
-
-Built automatically when `DEMO_BUILD_TOOLS=ON`:
-```bash
-cmake -S . -B build -DDEMO_BUILD_TOOLS=ON
-cmake --build build --target specplay
-```
-
-Or with all options:
-```bash
-cmake -S . -B build -DDEMO_ALL_OPTIONS=ON
-cmake --build build
-```
-
-## Code Architecture
-
-- **Minimal dependencies**: Only uses audio subsystem + miniaudio
-- **Self-contained**: No GPU, no platform layer (pure audio)
-- **Size**: ~250 lines (easy to extend)
-- **Format support**:
-  - `.spec` via SpecHeader parser
-  - `.wav` via miniaudio decoder (also handles .aif, .mp3)
-
-## Related Tools
-
-- **spectool**: Analyzes .wav → generates .spec (batch processing)
-- **specview**: ASCII visualization of .spec frequency content
-- **specplay**: This tool (playback + analysis)
-
-## Troubleshooting
-
-**"Failed to read SpecHeader"**
-- File is not a valid .spec file
-- Try with spectool to regenerate: `./build/spectool analyze input.wav output.spec`
-
-**"Peak exceeds 1.0! Will clip during playback."**
-- Spectrogram has too much energy
-- Likely needs regeneration after DCT changes
-- Or source .wav is already clipping
-
-**No audio output**
-- Check system audio device
-- Ensure 32kHz sample rate is supported
-- Try with a different .spec file (may be empty/silent)
-
-## Examples
-
-### Find all clipping samples
-```bash
-for f in assets/final/*.spec; do
-  ./build/specplay "$f" | grep "WARNING" && echo "$f"
-done
-```
-
-### Compare wav source to spec output
-```bash
-./build/specplay assets/originals/kick.wav
-./build/specplay assets/final/KICK.spec
-# Compare Peak/RMS values
-```
-
-### Quick loudness check
-```bash
-./build/specplay assets/final/KICK_606.spec | grep "RMS"
-# RMS > 0.3: loud, RMS < 0.1: quiet
-```
-
----
-
-**Last Updated**: February 6, 2026
-**Author**: Claude (AI assistant)
-**Status**: Production-ready, actively used for debugging