feat(targets): re-add lemma/lemmy/lemrd full 6-variant slots (Phase 2 done)

fix: isolate per-target failures + temp park family until phase 2

targets: lemer complete — all 6 quant slots verified e2e

feat: add quant field — (name, type, quant) is the composite target key

targets: uppercase gguf tags (Q4_K_M)

targets: swap mlx base from mlx-community to LetheanNetwork/lemer-mlx

feat: gguf wrapper + (name, type) composite target key

refactor: partition by type (mlx|gguf), drop owner hostname field

feat: initial LEM-Eval scaffold — target-driven 8-PAC runner