feat(audio): replace cues with austrian composer snippets

[dnim]

• Replace work start sound with Mozart's Eine kleine Nachtmusik
• Replace short rest sound with Strauss's The Blue Danube
• Add separate long rest sound with Beethoven's Ode to Joy
• Replace completion beep with Haydn's Surprise Symphony
• Increase completion beep volume for better audibility
• Update audio integration tests

[codecov]

Codecov Report

❌ Patch coverage is 90.90909% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.97%. Comparing base (3533642) to head (c97d00e).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/app.ts	84.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #20      +/-   ##
==========================================
+ Coverage   76.57%   77.97%   +1.39%     
==========================================
  Files           8        8              
  Lines         602      622      +20     
  Branches      151      161      +10     
==========================================
+ Hits          461      485      +24     
+ Misses        141      137       -4     

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