docs: README + MODEL_CARD for v0.6.4

v0.6.4: rnnt_phase11b + lm_amateur_3gram

morseformer v0.6.0 — Phase 5.8 EN-literary + streaming offline decoder

morseformer v0.5.4 — unified CLI + 4 presets

morseformer v0.5.3 — Phase 5.7 amateur-idiom curriculum (5NN + run-on UR/SK/KN/BK)

v0.5.2: inference-only digit-threshold fix (no new checkpoint)

v0.5.1: Phase 5.5 — long inter-word silences (rnnt_phase5_5.pt)

v0.5.0: Phase 5.4 acoustic — wider jitter + real-audio mix; cures hand-keyed CW

v0.4.1: confidence threshold default + LM rescoring with lm_phase5_2

morseformer v0.4.0 — Phase 3.4 + 3.5 (49-vocab, French CW with É/À/')

v0.3.0 release: Phase 3.3 multilingual prose acoustic model + streaming space-bug fix

v0.2.0: add Sébastien Derhy to acknowledgments

morseformer v0.2.0: Phase 3.2 anti-hallucination model + streaming decoder

Update README.md

morseformer v0.1.0 initial release

initial commit