Card: note the litert-lm 0.15 ExecutorMetadata update (weights unchanged)

Add ExecutorMetadata section required by litert-lm >= 0.15 (weights unchanged; still runs on 0.14)

Add ExecutorMetadata section required by litert-lm >= 0.15 (weights unchanged; still runs on 0.14)

LFM2.5-1.2B-Thinking LiteRT-LM: int8 linears-only (GSM8K 77% vs bf16 81, thought-channel native) + int4 736MB; CPU backend; conv-state prefill fix baked in

initial commit