Handle vendored descriptor.proto gracefully

[emcfarlane]

Upgrade protocompile to handle vendored descriptor.proto.

Fix resolver construction when compiled files include a vendored descriptor.proto. The buf descriptor extension (field 536000000 on FileDescriptorSet) fails protodesc validation when FileDescriptorSet is resolved from the vendored file rather than left as a placeholder, because it has no declared extension ranges. Skip prepending the buf descriptor proto when descriptor.proto is already in the compiled output.

Depends on bufbuild/protocompile#710

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Apr 17, 2026, 3:34 PM

[emcfarlane]

As an e2e example. The LSP will show errors when using features that are not suported/outside the provided descriptor.proto version. Here I use the dependency buf.build/protocolbuffers/wellknowntypes:v27.1 with an edition 2024 file with the some example features:

The build will also fail with the following errors:

custom.proto:11:16:cannot find message field `enforce_naming_style` in `google.protobuf.FeatureSet`
custom.proto:12:16:cannot find message field `default_symbol_visibility` in `google.protobuf.FeatureSet`
custom.proto:24:28:cannot find message field `large_enum` in `pb.JavaFeatures`