Cooper.Native.ResolverRef (Cooper v0.1.0)

@native("Cooper.Native.ResolverRef", "scan") implementation for RESOLVER_REF_RAW (casc.aether/casc_interp.aether): scans a !{name:payload} resolver reference (CASC.md §7.4) with genuinely unbounded brace nesting in payload, tracking depth as it goes.

Superseded by this token's earlier, ordinary-combinator form (one literal level of "{"/"}" tolerated, no deeper -- Aether tokens can't self-reference, so a fixed grammar can only ever hard-code a fixed nesting depth) once Ichor 0.1.1 added @native(...) at token position: what was a documented limitation ("realistic payloads don't nest deeper") is now simply not a limitation, at zero cost to every payload that never nested in the first place. Cooper.RefCommon .build_resolver_ref/2 -- the only consumer of this token's captured text -- already works on the raw span regardless of how deep it nests, so nothing downstream needed to change.