feat: add 90s-midi-composer skill and Neon Dreams demo

- SKILL.md: complete reference for creating 90s-style MIDI with Python/mido
- drum_reference.md: full GM drum kit note mapping
- compose_neon_dreams.py: 1.5 min A minor dance track at 128 BPM
- neon_dreams.mid: compiled 6-track MIDI (drums, pads, bass, synth lead, piano)

README.md

@@ -1,3 +1,20 @@
 # pi-midi-zone
-A place for pi to create music!
 
+A place for Pi to create music!
+
+## Contents
+
+### Skills
+
+- **skills/90s-midi-composer/** — Skill for creating authentic 90s-style MIDI music files using Python + mido. Generates General MIDI/SC-55 aesthetic tracks with classic dance beats, synth leads, pads, bass, and piano.
+
+### Examples
+
+- **examples/compose_neon_dreams.py** — Python script that composes a 90s dance track ("Neon Dreams"), 48 bars / 1.5 min / 128 BPM in A minor.
+- **examples/neon_dreams.mid** — Completed 6-track MIDI file. Uses fluidsynth to listen: `fluidsynth /path/to/FluidR3_GM.sf2 examples/neon_dreams.mid`
+
+## Quick Start
+
+1. Install: `pip3 install mido`, `sudo apt install fluidsynth fluid-soundfont-gm`
+2. Run: `python3 examples/compose_neon_dreams.py`
+3. Listen: `fluidsynth /usr/share/sounds/sf2/FluidR3_GM.sf2 neon_dreams.mid`