fix(ResultList): lazy citation fetch and SimpleLink event handlers

[thostetler]

Removes eager batch citation fetch from SimpleResultList that fired
export/agu API calls on every page load. Citations are now fetched
lazily in ItemResourceDropdowns when the share dropdown opens.

Also fixes SimpleLink event handler placement for Next.js legacyBehavior.

• Lazy citation fetch gated on share menu open state
• Remove batch fetch and prop threading from SimpleResultList/Item
• Move onMouseEnter/onTouchStart to child element in SimpleLink
• Add tests for lazy fetch behavior

[codecov]

Codecov Report

❌ Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 61.4%. Comparing base (16137e0) to head (b6cb21d).

Files with missing lines	Patch %	Lines
...mponents/ResultList/Item/ItemResourceDropdowns.tsx	95.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #790     +/-   ##
========================================
+ Coverage    61.3%   61.4%   +0.2%     
========================================
  Files         307     308      +1     
  Lines       35535   35740    +205     
  Branches     1553    1577     +24     
========================================
+ Hits        21761   21943    +182     
- Misses      13738   13761     +23     
  Partials       36      36             

Files with missing lines	Coverage Δ
src/components/SimpleLink/SimpleLink.tsx	95.9% <100.0%> (ø)
...mponents/ResultList/Item/ItemResourceDropdowns.tsx	62.4% <95.0%> (ø)

... and 6 files with indirect coverage changes

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