Bound parser depth and validate supplied ASTs before recursive traversal

[Corvette052]

Addresses publicly disclosed GHSA-vfj7-8cjw-p6xm: GHSA-vfj7-8cjw-p6xm. Parser brace/parenthesis nesting is bounded at 128. Iterative depth/path validation precedes compile, expand and stringify, including supplied ASTs. Deep/cyclic inputs throw SyntaxError; shared acyclic nodes remain supported. Callers must handle validation errors. This does not address every expansion-resource hazard. Adds Mocha regressions for 12,000-level ASTs, cycles, 4,000-level patterns, ordinary ranges, 64-level nesting and shared nodes. Validation: npm install --ignore-scripts --no-package-lock; npm test: 899 passing on Node 24.19.0. No package version change. Maintainer feedback welcome on depth and error semantics.

[ulises-jeremias]

I independently reviewed and tested this head on Node 24.17. The suite passes (899 tests), but there is still a hang through the caller-supplied AST path: the preflight only validates nodes, while expand() follows parent pointers in while loops.

Reproducer (the nodes graph is acyclic):

const ast = { type: 'root', nodes: [] };
const paren = { type: 'paren', nodes: [{ type: 'text', value: 'x' }] };
ast.nodes.push(paren);
paren.parent = paren;
require('./lib/expand')(ast);

At this PR head (a795ee8) it does not terminate (I stopped it after 2 seconds). The same case on PR #87 (d44b9b1) rejects with RangeError: AST parent chain contains a cycle; that implementation also passes its 908 tests. Please validate parent chains (or guard queueOwner/the expand parent walks) and add this regression before relying on the AST preflight as a complete fix.