Add MIDIUtil examples with working 90s dance compositions

- 01-basic-chord.py: chord progressions (C major)
- 02-90s-dance-track.py: 5-track 90s dance (arp, bass, pads, drums, piano)
- 03-arpeggiator.py: reusable arpeggio generator with dir/type options
- 04-single-note.py: minimal single-note example
- Rewrite compose_neon_dreams.py: cleaner track functions, proper velocity=0 note_off, tick helper
- Add README.md with setup and API reference

Uses MIDIUtil library (beats-based API) instead of mido
(clocks-based API)

examples/04-single-note.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+"""
+04-single-note.py - Single note example (from MIDIUtil docs, adapted)
+Creates a minimal single-track MIDI file with one note.
+Reference: examples/single-note-example.py from MIDIUtil repo
+"""
+from midiutil import MIDIFile
+
+# Create the MIDIFile Object
+my_midi = MIDIFile(1)
+
+# Add track name and tempo
+track = 0
+time = 0
+my_midi.addTrackName(track, time, "Sample Track")
+my_midi.addTempo(track, time, 120)
+
+# Add a single note
+channel = 0       # MIDI channel 1
+pitch = 60        # MIDI note number (60 = middle C / C4)
+duration = 1      # Duration in beats (1 = quarter note)
+volume = 100      # MIDI velocity 0-127
+
+my_midi.addNote(track, channel, pitch, time, duration, volume)
+
+# Write to disk
+with open("single-note.mid", 'wb') as binfile:
+    my_midi.writeFile(binfile)
+
+print("Written: single-note.mid")
+print(f"  Note: C4(60) on channel {channel}, {duration} beat(s) at 120 BPM")