docs(board): repair ledger — restore full rebased content (prior commit had placeholder truncation)

Previous commit 74e2d9e accidentally truncated the file to ~2.5 KB
(just the rubrics header). This commit restores the full 88 KB
rebased ledger: current main content (commit a6797ad with all six
2026-05-06/2026-05-07 dated sections from PRs #345/#346/#347/#348)
+ the unique 2026-05-07 CYCLE-ACCUM-1 + LADYBUG-EQUIV-1 dated section
appended at the end.

Author: AdaWorldAPI