fix(ui): render molecular formula numbers as subscripts

[vcnainala]

Summary

• Adds a shared MolecularFormula Vue component and parseMolecularFormulaDisplayParts utility to render molecular formula counts as subscripts (e.g. C₉H₈O₄).
• Updates all user-facing molecule views that display molecular formulas: sample/dataset/study sidebars (MolecularInfoPanel), molecule cards (MoleculeCard), and the public studies header (Public/Studies).

Closes #1432

Test plan

• Open a public sample page with molecular info in the sidebar and confirm formula numbers render as subscripts
• Open a molecule card listing (e.g. dashboard compounds) and confirm subscript formatting
• Open a public studies page for a molecule and confirm the header molecular formula uses subscripts
• Verify formulas that previously included HTML from CAS (e.g. CH<sub>2</sub>O) still render correctly after tag stripping

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.58%. Comparing base (632c381) to head (878bd44).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1461      +/-   ##
============================================
- Coverage     76.59%   76.58%   -0.01%     
  Complexity     3590     3590              
============================================
  Files           249      249              
  Lines         13510    13510              
============================================
- Hits          10348    10347       -1     
- Misses         3162     3163       +1     

Flag	Coverage Δ
unittests	76.58% <ø> (-0.01%)	⬇️

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