Qualify nested-type refs shadowed by a sibling of the same simple name

[ghostdogpr]

Problem

qualifyReferences (used by ProtobufCodec.render and Service.render) rendered a reference to a nested type as just its bare simple name whenever the referencing scope was enclosed by the target's parent:

val inScope = scope == parent || (scope.length > pl && scope.charAt(pl) == '.' && scope.startsWith(parent))
if (inScope) name else path

This ignores proto3's innermost-scope-first name resolution. If the current message has its own nested type of the same simple name, that inner type shadows the intended one, so the emitted bare name binds to the wrong message. The .proto still parses, but the field now points at a different type — a silently corrupted schema.

Concrete case

Outer has nested Outer.Inner and nested Outer.Deep; Outer.Deep has its own nested Outer.Deep.Inner. A field in Outer.Deep referencing the outer Outer.Inner rendered as bare Inner, which under proto3 rebinds to Outer.Deep.Inner.

Fix

Resolve the bare name the way proto3 would — from scope outward to the root, first same-named declared type wins — and keep the bare name only when it lands on the intended target. Otherwise fall back to the qualified path (the existing out-of-scope rendering).

Test

ProtobufRenderSpec: a sibling-shadowing scenario asserts the ref is qualified to Outer.Inner. Red before the fix (rendered bare Inner), green after. Full core suite (138) and grpc RenderSpec/FileDescriptorSpec (43) remain green.