Replace jargon-heavy terminal-style UI with plain-language views.
New data model: wallets (HD or private key) contain addresses.
Main view lists all addresses grouped by wallet with balances.
HD wallets get a "+" to add addresses; key wallets have one.
Two import paths: recovery phrase and private key.
All labels use plain English, full-sentence errors, inline help
text. README updated with full UI philosophy, language guide,
data model, and navigation docs.
Makefile, Dockerfile, CI workflow, prettier config, manifests for
Chrome (MV3) and Firefox (MV2), source directory structure, and
minimal test suite. All checks pass.
