Anglicize tippen's codebase and finish pending UI/curriculum cleanup

- Rename all German identifiers, types, mode ids, file names, CSS classes
  and data-attributes to English throughout tippen/src; only user-facing
  text (lesson titles, word lists, labels, spoken praise) stays German.
- Add a word/nonsense-word list to the "Übung: die Grundstellung" home-row
  lesson in the curriculum.
- Remove the unused HandHint component and speech.ts, and carry forward
  the in-progress App.tsx/component/generator/progress edits from other
  sessions.
- Refresh the regenerated music-library cache index.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tippen/src/lib/engine.ts

@@ -86,7 +86,7 @@ export function press(state: RunState, key: string, now: number): [RunState, Run
   if (expected === undefined) return [state, []];
 
   // The layout is what decides case, not the run: typing "A" where "a" is wanted is
-  // correct. Capitals are their own lesson (Welt 4), and that lesson's target text
+  // correct. Capitals are their own lesson (world 4), and that lesson's target text
   // carries the capital, so this comparison still teaches Shift where it matters.
   const correct = key.toLowerCase() === expected.toLowerCase();
   const startedAt = state.startedAt ?? now;
@@ -117,7 +117,7 @@ export function press(state: RunState, key: string, now: number): [RunState, Run
 }
 
 /** Give up on the rest of the line - what Escape does. The run is still graded on what
- * was typed, so a half-finished Blasenplatzen round still earns its Perlen. */
+ * was typed, so a half-finished bubbles round still earns its pearls. */
 export function abandonRun(state: RunState, now: number): RunState {
   if (isFinished(state) || state.startedAt === null) return state;
   return { ...state, finishedAt: now };