Fix classical/singalong rhythm bugs and remove non-public-domain songs

- buildClassicalNotes() had an unreachable return after the note-building
  chain, so simplifyNotes() (the Full/Simple note-density toggle) was never
  applied to any isClassical piece — fixed by assigning to a variable first.
- Jingle Bells' note durations used an eighth-note-heavy pattern that
  compressed the tune to roughly half its correct length instead of the
  familiar quarter/half-note "Jingle bells, jingle bells" cadence — replaced
  with a standard, measure-verified rhythm.
- Drunken Sailor inserted a stray extra beat between each of its 3 passes
  (t+=q, one full quarter note tied to the beat grid) which broke the 4/4
  pulse; changed to an off-grid pause. Also extended its chord backing to
  cover the chorus (mm9-16), which previously had none on repeat passes.
- Removed O Fortuna (Orff, 1936) and Sabre Dance (Khachaturian, 1942) from
  Classical, and Rudolph the Red-Nosed Reindeer (1949), Frosty the Snowman
  (1950), and Winter Wonderland (1934) from Christmas — none of these are
  actually public domain (all still under active copyright), despite being
  filed under a "public domain compositions" list.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PbwKCCj1vwAoqgRYDoqgeL

README.md

@@ -25,7 +25,7 @@ Works with **keyboard**, **Wii Rock Band drums**, **Xbox/PS Rock Band drums**, *
 ## Features
 
 - **18 Genres** across two modes: synth orchestra songs + drum beat patterns
-- **124 synth pieces** with full synthesized orchestra background
+- **119 synth pieces** with full synthesized orchestra background
 - **120 drum patterns** across 8 genres
 - **Note density toggle** — switch between Full and Simple (fewer notes for beginners)
 - **Drums or Orchestra mode** — choose whether pad hits play drum sounds or the actual melody note
@@ -82,7 +82,7 @@ Works with **keyboard**, **Wii Rock Band drums**, **Xbox/PS Rock Band drums**, *
 - Scarborough Fair (English Medieval)
 - My Bonnie Lies Over the Ocean (Scottish, 1881)
 
-### Christmas (20 songs)
+### Christmas (17 songs)
 - Jingle Bells (1857)
 - Silent Night (1818)
 - Deck the Halls (1862)
@@ -98,9 +98,6 @@ Works with **keyboard**, **Wii Rock Band drums**, **Xbox/PS Rock Band drums**, *
 - What Child Is This (English, 1865)
 - Angels We Have Heard on High (French, 1862)
 - O Holy Night (A. Adam, 1847)
-- Rudolph the Red-Nosed Reindeer (J. Marks, 1949)
-- Frosty the Snowman (S. Nelson, 1950)
-- Winter Wonderland (F. Bernard, 1934)
 - Good King Wenceslas (Finnish, 1582)
 - We Three Kings (J.H. Hopkins Jr., 1857)
 
@@ -144,10 +141,9 @@ Works with **keyboard**, **Wii Rock Band drums**, **Xbox/PS Rock Band drums**, *
 - The Cascades (Scott Joplin, 1904)
 - Pineapple Rag (Scott Joplin, 1908)
 
-### Classical (26 pieces)
+### Classical (24 pieces)
 - Beethoven's 5th (Opening)
 - Hall of the Mountain King (Grieg)
-- O Fortuna (Orff)
 - Ride of the Valkyries (Wagner) — Apocalypse Now
 - Mars, Bringer of War (Holst)
 - Toccata & Fugue in D Minor (Bach)
@@ -156,7 +152,6 @@ Works with **keyboard**, **Wii Rock Band drums**, **Xbox/PS Rock Band drums**, *
 - Also Sprach Zarathustra (R. Strauss) — 2001: A Space Odyssey
 - Barber of Seville Overture (Rossini) — Bugs Bunny
 - The Blue Danube (J. Strauss II) — 2001: A Space Odyssey
-- Sabre Dance (Khachaturian)
 - Night on Bald Mountain (Mussorgsky) — Fantasia
 - Sorcerer's Apprentice (Dukas) — Fantasia
 - Swan Lake Theme (Tchaikovsky)