Entity Footnotes patch v1.0.0

First release as a standalone KOReader user patch. See the README for install instructions and background.

Underlines AI-identified characters, historical figures, locations, and terms directly in the reading text and shows the AI description in a tap-to-reveal popup. Scanning is chunked and non-blocking so page turns stay responsive.

Requires ultimatejimmy/xray.koplugin already installed and configured.