Collects the grouping-relevant literals of a subtree: numbers above 2, address literals
and hex string literals. A bare literal indexing an array-like value or bounding a slice
stays out as positional, matching Aderyn; a mapping key counts, it is configuration data.
The semantic value of a literal, the grouping key: two spellings of the same number
(100, 0x64, 1e2) or the same unit-scaled amount (1 ether, 1e18) are one value.
A numeric literal under a value-changing unary operator denotes a DISTINCT constant, so
-5 and ~5 never group with the bare 5.