docs(5285): correct Story 1 scope — Wallet.hs is already migrated
Pre-flight grep on the implementation pass showed lib/wallet/src/Cardano/
Wallet.hs already imports certificateFrom{Delegation,Voting}ActionLedger
from Cardano.Wallet.Shelley.Transaction.Ledger and its 4 callsites at
2729, 2738, 3533, 3542 already use the *Ledger variants. The Phase-0
research had it wrong; plan.md, quickstart.md, and tasks.md inherited
the error. Spec.md was correct (line 18 already named the single
caller).
Slice scope shrinks from 'edit two files + delete two + cabal prune' to
'edit Shelley/Transaction.hs + delete two + cabal prune'. SC-001/SC-002,
FR-003, and the byte-equivalence proof are unaffected.