v2.0.8.7

OFF v2.0.8.7 - in-wallet Codex reader

Adds Phase B of the on-chain Codex reader to the Qt wallet. The Codex
tab now displays the Lovecraft canon being inscribed into chain history
post-Restoration: a Table of Contents on the left, paginated reader in
the center (matching the website e-reader at https://23skidoo.info/codex/),
and a Frontier panel on the right that tails new fragments live as
blocks are mined.

Carries forward all v2.0.8.6 fixes (OFFSIG self-validate, pool-coinbase
wiring). v2.0.8.5 users with gen=1 still need to upgrade — the wallet
crash on sync past block 999999 is fixed here.

No consensus / net compat changes since v2.0.8.5. PROTOCOL_VERSION 90003.
Same depends/ stack.