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

CLAUDE.md

@@ -159,7 +159,6 @@ Add a new genre called **"Classical"** with the following pieces. Each piece nee
 |-------|----------|-------|
 | Beethoven's 5th (Opening) | Beethoven | DA DA DA DUM — 3 same pad + 1 different |
 | Hall of the Mountain King | Grieg | Starts slow, accelerates — great difficulty curve |
-| O Fortuna | Orff | Heavy rhythmic hits, powerful |
 | Ride of the Valkyries | Wagner | Galloping rhythm pattern |
 | Mars, Bringer of War | Holst | Heavy 5/4 march |
 | Toccata & Fugue in D Minor | Bach | Famous DUN DUN DUN opener |
@@ -168,13 +167,14 @@ Add a new genre called **"Classical"** with the following pieces. Each piece nee
 | Also Sprach Zarathustra | Strauss | DA DAAAA DA DUM (2001 theme) |
 | Barber of Seville Overture | Rossini | Bugs Bunny classic |
 | The Blue Danube | Strauss Jr. | Waltz rhythm |
-| Sabre Dance | Khachaturian | Very fast and fun |
 | Night on Bald Mountain | Mussorgsky | Fantasia — dark and dramatic |
 | Sorcerer's Apprentice | Dukas | Fantasia — Mickey Mouse |
 | Swan Lake (Theme) | Tchaikovsky | Elegant waltz |
 | Morning Mood | Grieg | Peer Gynt — gentle build |
 | In the Hall of the Mountain King | Grieg | (same as above, confirm not duplicate) |
 
+> **Not actually public domain — do not re-add:** O Fortuna (Orff, 1936; composer d. 1982 — still under copyright until 2032 in the US / 2052 in the EU) and Sabre Dance (Khachaturian, 1942; composer d. 1978 — still under copyright until 2048 in the EU) were removed from the repo on this basis. The rest of this table is genuinely public domain (composers who died before ~1955, or works published before 1930).
+
 #### How Classical Mode Should Work
 1. Player selects a classical piece
 2. Game starts with countdown