fix: link OpenMP on Linux for llama.cpp parallelism

llama.cpp uses OpenMP (GOMP_barrier, GOMP_parallel) on Linux.
Without -lgomp the linker fails with undefined references.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Frank Guo

cmd/rekal/cli/nomic/nomic_cgo.go

@@ -8,6 +8,7 @@ package nomic
 #cgo LDFLAGS: -L${SRCDIR}/../../../../.deps/llama.cpp/build/ggml/src -lggml -lggml-base -lggml-cpu
 #cgo LDFLAGS: -L${SRCDIR}/../../../../.deps/llama.cpp/build/common -lcommon
 #cgo LDFLAGS: -lstdc++ -lm
+#cgo linux LDFLAGS: -lgomp
 #cgo darwin LDFLAGS: -L${SRCDIR}/../../../../.deps/llama.cpp/build/ggml/src/ggml-metal -lggml-metal
 #cgo darwin LDFLAGS: -L${SRCDIR}/../../../../.deps/llama.cpp/build/ggml/src/ggml-blas -lggml-blas
 #cgo darwin LDFLAGS: -framework Foundation -framework Metal -framework MetalKit -framework Accelerate