Dollar Escape

Plain math:

$E = mc^2$

Escaped dollars:

$5 should render as $5.

this is a $100 phone
this is a @@VYASA_DOLLAR@@100 phone
this is a $100-$200 phone
this is a @@VYASA_DOLLAR@@100-@@VYASA_DOLLAR@@200 phone

\\$ should render as \@@VYASA_DOLLAR@@.

\@@VYASA_DOLLAR@@ should render as \@@VYASA_DOLLAR@@.

Inline code should stay literal: \$ and \\$.

Fenced code should stay literal:

$E = mc^2$
\$5
\\$
\\\$

More literal dollar cases:

$5 at start of sentence should stay literal.
Price in parens ($25) should stay literal.
Comma/period: $1,299.99 and $20.
Range with spaces: $100 - $200 should stay literal.
Range without spaces: $100-$200 should stay literal.
Path-ish text: cost/$100/file should keep literal $.

Mixed with math:

Math still works: $a^2 + b^2 = c^2$.
Currency and math same line: pay $20 and solve $x+1=2$.
Escaped currency near math: @@VYASA_DOLLAR@@20 and $x=2$.

Escaped edge cases:

@@VYASA_DOLLAR@@ at end of line should stay literal.
Double escaped then dollar: \@@VYASA_DOLLAR@@ should stay literal as \@@VYASA_DOLLAR@@.
Brackets and escaped: price is @@VYASA_DOLLAR@@30 should show $30.

Inline/fenced code edge cases:

Inline code: $100, \$100, price=$100, x="$100".

price = "$100"
escaped = "\\$100"
expr = "$x^2$"  # should remain literal in code

Multiline KaTeX blocks:

$$ f(x) = x^2 + 1 \quad\text{and}\quad g(x) = \frac{1}{x+1} $$

Currency around block math:

Price before block is $50 (literal), math block below should render:

$$ \int_0^1 x^2,dx = \frac{1}{3} $$

Escaped currency after block should stay literal: @@VYASA_DOLLAR@@75.