chore: strip private files for public sync

i18n: translate all code, comments and scripts to English

chore: translate Makefile to English, clean README for open-source, extend public sync exclusions

fix(push-public): rm private files before git checkout to prevent untracked conflict

fix(push-public): add cleanup trap + fix dirty-check condition

chore: add push-public script for dual-repo workflow

docs: comprehensive doc improvements across all pages

docs: move all MDX files under openrag/ subfolder

chore(docs): trigger Mintlify redeploy for basePath /openrag

docs: add basePath /openrag for multi-project docs support

feat(admin): overhaul admin panel with 8 tabs

feat(api): add /stats, /history, fix /collections + /documents

docs: update auth documentation to reflect JWT + PostgreSQL user system

feat(frontend): real JWT auth + Users admin tab

feat(auth): PostgreSQL JWT authentication with user management