Revert badges to flat style

Conservative key features; add Raon-OpenTTS-Eval Wild benchmark TBD

Unify image width to 600; use flat-square badges on 0.3B

Remove <br> to keep badges in one line

Fix links and add datasets field

Replace badge links with text links

Add Tech Report / Code / Model / 1B badge row

Unify citation; update tags

Fix inference link to GitHub, unbold 1B coming soon, fix benchmark model name

Rename Raon-TTS to Raon-OpenTTS throughout README

initial commit