feat: Add LlamaCpp provider for local NIF-based LLM inference #21

Job	Run time
Compile & Warnings	23s
Formatting	17s
Tests (ubuntu-latest / OTP 27.2 / Elixir 1.18.3)	28s
Tests (ubuntu-latest / OTP 27.2 / Elixir 1.17.3)	24s
Credo	20s
Dialyzer	32s
Publish to Hex	0s
	2m 24s

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