a path literal with a digit-leading first component fails to lex

[wyattgill9]

$ fix parse -E '/123abc'
error: parse error at 1:1: Unexpected token '/'.

$ nix-instantiate --parse -E '/123abc'
/123abc

Only the first component is affected. A digit-leading component anywhere else lexes fine:

$ fix parse -E '/a1'
{ "_type": "ExprLiteral", ... }

This shows up on content-addressed store paths written as path literals, so exposure grows as CA derivations spread. In the pinned nixpkgs corpus it is hit by lib/tests/modules/pathWith.nix:63.

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fix 0.3.0 at 1f1a99cf, built -Doptimize=ReleaseSafe with Zig 0.16.0, darwin/aarch64. Reference implementation is Nix 2.34.8.