chore(i): some some general updates

apps/test/content/posts/katex-test.md

@@ -71,3 +71,11 @@ $$ \ce{CO2 + C -> 2 CO} $$
 $$ \ce{Hg^2+ ->[I-] HgI2 ->[I-] [Hg^{II}I4]^2-} $$
 
 $$C_p[\ce{H2O(l)}] = \pu{75.3 J // mol K}$$
+
+## $\KaTeX$ in headings
+
+This is a bug:
+
+```latex
+## $\KaTeX$ in headings
+```

apps/test/content/posts/mathjax-test.md

@@ -118,6 +118,12 @@ U \ar@/_/[ddr]_y \ar@{.>}[dr]|{\langle x,y \rangle} \ar@/^/[drr]^x \\
 \end{xy}
 $$
 
+## \$\\text{MathJax}\$ in headings
+
+```latex
+## \$\\text{MathJax}\$ in headings
+```
+
 ## More
 
 ### Dark Mode Adaptation