Adds a French translation of the main README for francophone users, plus a
language link at the top of the English README. Prose-only translation:
all slash-commands, code blocks, install commands, URLs, image alt-text and
the 'See it work' transcript are kept verbatim in English.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Smarto