[fatihcvs]

Summary

Closes #7.

Both MCP size guards now use Buffer.byteLength(value, "utf8") instead of JavaScript string length. Emoji/CJK frames can no longer exceed the configured byte limits while passing the character-count checks. Existing error responses and recovery behavior are preserved.

Verification

• Seven transport regressions exercise ASCII, emoji and CJK frames at the 1 MiB boundary and one byte over it, plus the 2 MiB buffer limit across chunks. The three Unicode rejection/buffer tests fail on the original implementation; all seven pass after the fix.
• Deterministic decoded chunks are fed to the actual server in isolated child processes. Existing real-stdio tests also pass in the full suite.
• npm run build, npm run typecheck: pass.
• npm test: 249 pass, none skipped.
• npm run test:contract: 2 pass.
• New test file passes Prettier. The repository-wide npm run format:check reports 73 existing files, including the original src/mcp/server.ts (checked separately from HEAD). This PR keeps the production change to the two guards rather than reformatting unrelated code.

Developed with OpenAI Codex assistance. No dependency changes.