docs(coil): fix seam-ledger rows the #71 rename left pointing at t3x names (#116)

Four rows in the ledger still described the update-delivery seam with its
pre-rename identifiers: a `t3xUpdate` bridge object, four `t3x:update-*`
channel constants, three `t3xUpdate` handlers, and interfaces at
`src/t3x/updateDelivery.ts`. None of those exist — the code calls them
`coilUpdate`, `coil:update-*`, `getCoilUpdateState` / `restartIntoUpdate` /
`dismissCoilUpdate`, and `src/coil/updateDelivery.ts`.

The ledger is the fork's map of its own upstream surface, so a row naming a
symbol that no longer exists is worse than no row: it reads as verified.

Not a blanket rename. `scripts/t3x/**`, `.github/workflows/t3x-*.yml` and the
`t3x-sync` label all kept the old name through #71, and line 49's note about
the rename itself is correct history. Only source namespaces and docs moved.

Also corrects the header total, which read +2621 against a measured +2622.
That is the third time the totals have been wrong when checked (+1616 vs
+1627 on 08-05), which is the file's own "regenerate before trusting it"
advice earning its place.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: radroid