docs: link the demo video and write-up from the README (submission deliverables)

fix(deploy): pin Gradio to 6.18.0 for Space/local parity (intro + layout)

build: Space deps for Kokoro voice (python 3.11, espeak-ng, spacy)

docs: submission README — track/badge tags, write-up, sound warning

Day 1: basic chat loop with Hollow character

Initial commit