fix: restore LaTeX subscripts on Ihara constant page

[Chessing234]

Summary

• Restore proper _ subscripts inside math mode on the 33a constant page
• Reverts the regression from fix: escape inline subscripts on Ihara constant page #113 where \_ was used inside $...$, which renders literally instead of as subscripts

Test plan

• Build the Jekyll site and confirm the page title shows F₂ correctly
• Check the opening paragraph renders $C_{33}$ and $\mathbb{F}_2$ properly

Made with Cursor

[Chessing234]

Merged #113 accidentally escaped underscores inside math delimiters — so the title showed a literal backslash instead of F₂. This puts normal LaTeX subscripts back.