README: open with the "superstructure over text" pitch (#467) Lead the intro with the framing line: programming languages are the superstructure over machine opcode; Coga is the superstructure over text — the structure, reuse, and legibility that turn one-off prompts into a system you own. Sets up the existing "don't don't think" tagline and the what-it-is paragraph that follow. Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>