[s-kris]

Fixes #332.

What was wrong

findAll in src/matcher.ts, which css-select calls for querySelectorAll, built its result like this:

if (childs) result = result.concat(findAll(test, childs));

1. Every concat copies all the matches found so far, once per child, so the search was quadratic in the number of siblings.
2. It recursed once per nesting level, so very deep documents overflowed the call stack.

The change

findAll now walks the tree depth-first with an explicit stack and pushes matches onto one array. Children are pushed in reverse, so they come off the stack in document order. The matches and their order are unchanged.

Measured

querySelectorAll('img') on <div> + N sibling <img>, Node 24:

Siblings	Before	After
40,000	2,418 ms	4 ms
90,000	12,057 ms	6 ms
1 MB article, 15,000 nested images	95 ms	7 ms

On 10,000 nested <div>s, querySelectorAll('div') threw Maximum call stack size exceeded before the change and returns 10,000 elements after it.

Tests

test/tests/queryselectorall-scaling.js covers three things:

1. Document order for nested matches, including *.
2. 100,000 siblings in well under a second. The bound is generous on purpose, so it cannot flake on a slow CI machine, while the old code would take over 15 seconds.
3. 10,000 levels of nesting without a stack overflow.

bun run test passes: 325 passing, 13 pending, as before. The benchmark's node-html-parser line is unchanged at about 1.06 ms per file.

bun run lint fails on a clean checkout of main too, with Failed to load plugin '@typescript-eslint', so I could not lint this change locally.