Retire the reading ledger once the packer asks the reader

What this is

tests/format/reading-ledger.json (14,249 lines, 2,374 rows) plus its generator, loader, test and tests/format/reading-invariant.test.ts (1,068 code lines) is the depth-5 allowlist of documents whose reading a reflow join still changes. Every row is render-equal and idempotent today; the ledger records normalization debt, not corruption. #195 exports the reader's per-line verdict to the packer, after which the five families it names empty (#185's retirement rule).

The change

When #195 lands and the families are empty, delete the ledger, its writer and its loader; the reading INVARIANT stays as a test over the corpus and the default grid, not a ledger. Source: fence-scripts.md row RETIRE-AFTER #195; fence-tests.md removal 1.

Gate

bun run reading-ledger reports zero rows on the default grid before deletion; the invariant test remains and is green; 15,003 lines gone.

Wait for #195 and confirm the five named families are empty. Run bun run reading-ledger on the default grid, then inspect tests/format/reading-ledger.json, its generator and loader, and tests/format/reading-invariant.test.ts. Done means the ledger, writer, and loader are removed, the invariant remains green, and the command reports zero rows before deletion.