Blog: All links section at end, dedupe inline URLs

Blog: fix typo, clarify reward CSV paths and D1

Blog: clearer problem synopsis, Colab links, resolve URL for chart

docs(Blog): CSV stats, 0.6 by task, tools list, reward_curve copy.png figure

docs(Blog): Colab + Space tree links, Qwen3-0.6B run, human read on ~160/~0.6 curve

docs: add Blog.MD writeup for HF Space; README links Hub + YouTube placeholder