docs: enhance README (badges, model table, quickstart)

[stukenov]

Summary

OSS marketing pass on the project README. All additions use real numbers, configs, and commands already present in the repo — no invented benchmarks or metrics.

Changes

• Added a badge row: MIT license, Python 3.10+, Hugging Face (stukenov).
• Sharpened the one-line value prop: open Kazakh small language models, trained from scratch (14M–600M).
• Added a Model Architectures table with verified hidden/layers/heads/context pulled directly from configs/experiments/ (exp004 14M, exp013 50M, exp014 150M, exp020 300M, exp023 587M).
• Added a ## Related projects section linking the broader Kazakh-language AI stack.

Notes

• Marketing-pass enhancement only: existing content, structure, and voice are preserved.
• LICENSE (MIT) was left untouched.

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