Mobile width fix, 6/8 crash fix, more arpeggio+Giuliani variants

- PhraseSheetMusic: min width per bar scales with notation density
  (16ths 320px, 8ths 260px, quarters 210px) — narrow screens wrap into
  more rows instead of clipping notes off-screen.
- 6/8 crash fixed at the root: melody templatesFor had no 6/8 templates
  (empty pool -> pick on empty array). Added 6/8 template sets for levels
  1/2 plus an empty-pool fallback guard so generators can never pick from
  an empty array again (any meter/level combination stays playable).
- More arpeggio broken-chord figures: 1-3-5-3, 1-2-1-3-2-1, 1-5-4-5-3-5,
  1-3-2-5-3-2.
- More Giuliani patterns: p-i-a-i (wide), p-m-a-m-i, p-i-m-a-m-i (waltz
  feel), p-i-m-a-i-a.
- Tests 179/179.

src/components/PhraseTrainer.tsx

@@ -647,6 +647,10 @@ export const PhraseTrainer = forwardRef<PhraseHandle, PhraseTrainerProps>(
                                                 <option value="1325">1-3-2-5(8)</option>
                                                 <option value="1535">1-5-3-5(8)</option>
                                                 <option value="12353">1-2-3-5-3</option>
+                                                <option value="1353">1-3-5-3</option>
+                                                <option value="121321">1-2-1-3-2-1</option>
+                                                <option value="15453">1-5-4-5-3-5</option>
+                                                <option value="132532">1-3-2-5-3-2</option>
                                             </optgroup>
                                         </select>
                                     </label>