docs: move NeonDB tables image to assets and document serverless schema in README

docs: add application page screenshots and insert showcase section in README

style: crop blank top/bottom padding from README banner image

docs: synthesize actual logo into a rectangular banner for README header

docs: update README to use actual high-res QuantIQ pulse logo

docs: update README banner image to match the actual QuantIQ circular heartbeat logo

docs: rewrite README with comprehensive architecture, rationale, and tech deep-dive