Ensure protobuf targets build in order and fix Lua include casing

[GersonHMG]

Summary

• gate the generated proto library on the ExternalProject protobuf build/install so the first build succeeds
• ensure the protobuf library target in src/protobuf waits for the external build to finish before Qt autogen runs
• correct the Lua bindings include to match the lowercase header name on case-sensitive filesystems

Testing

• cmake --build build --config Release -- -j1

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Codex Task