Update Readme.md for submission

feat: add field notes blog post, badge tags (off-brand, off-the-grid, field-notes)

feat: add demo video and LinkedIn post links to README

chore: pin Space to profile

fix: short_description under 60 chars, broaden from engineers to everyone

fix: backfill only updates related_ids (not wipe claims/recall), raise BGE threshold to 0.62, README hackathon tags

feat: add backend, frontend, seed data, and HF Spaces wiring

initial commit