docs: add Korean translation of README.md

[minhchee]

Description

Adds README.ko.md — the complete Korean (ko) translation of the root README.md.

Details

• Translated all sections: intro, "why this exists", comparison table, 30-second start, framework integrations (Mastra / LangChain / MCP / ChatGPT), the 6 protocol primitives, live proof, on-chain artifacts, architecture, verification mechanisms, status, contributing, documentation index, related ecosystems, the autonomous bounty hunter, and the live safety badge.
• Preserved every Bash / TypeScript / Python / JSON / Markdown code block verbatim.
• Preserved all URLs, shields.io badge markdown, EVM contract addresses, and Markdown tables.
• Pure documentation — no behavioral change, safe for CI.

Verification

• Markdown code fences balanced: 24 backtick fences (even).
• Line endings: LF only (no CRLF).

Context

Follows the same contribution pattern as the existing AIP-1/2/3/4 Korean translations. Root documentation previously had zero translations while specs/ carried 7 languages — this closes part of that gap for Korean-speaking agent builders.