docs(readme): fix accidental wrong-README upload — restore model card with GPU hardware + naming corrections

docs(readme): fix remaining 'CPU-only' caveat (training was on RTX 3080 Ti, paged_adamw_8bit, 4-bit)

docs(readme): correct hardware (RTX 3080 Ti, bf16, paged_adamw_8bit) + project naming (QuantumAI Blockchain is the chain; Qubitcoin/QBC is the currency)

initial: aether v5.2 LoRA (Qwen2.5-7B-Instruct, step 3200, +9.7pp ARC-C vs v5.1.1)

initial commit