bump(reach-edu): corpus binaries move to content-addressed storage

Carries the client repo from 320 MB to 24. Its 34 corpus PDFs now live once in
bin/, compressed and addressed by hash, with the publisher's original beside
each; every wrapper points at its object; the 156 MB 2026-07-28 snapshot moved
out of the tree; and the last 11 LFS-tracked binaries went into git directly,
which retires LFS and makes the repo safe for jj.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BocV5c3MSp3o7Zo4DyXrz5

Author: mpstaton