Fix adapter caller_already_converted for re-exporter chains

[avrabe]

Part of #69, depends on #72

Task

With custom handle tables, the re-exporter's code chains: slab_lookup → custom resource.rep → raw_ptr. The downstream adapter (re-exporter → definer) must NOT call resource.rep again.

Implementation

Files: meld-core/src/resolver.rs, meld-core/src/adapter/fact.rs

In the double borrow detection section of resolve_with_hints, after existing name-matching detection:

for site in &mut graph.adapter_sites {
    if graph.reexporter_components.contains(&site.from_component) {
        for op in &mut site.requirements.resource_params {
            if !op.is_owned && op.callee_defines_resource {
                op.caller_already_converted = true;
            }
        }
    }
}

Branch

feat/per-component-handle-tables

Acceptance

cargo test --package meld-core passes.