Decouple the /balance empty-state guard into three explicit states via a
new pure helper `deriveLandingState` (empty / accounts-no-snapshot /
populated). Having accounts but no snapshot no longer strands the user on a
snapshot-only onboarding card: each state now renders navigation tiles
(HubReportNavCard, modeled on the Reports hub), and "Manage accounts"
(/balance/accounts) is reachable in every state, including the populated
dashboard.
- Remove BalanceOnboardingCard (component + test) and the dead
balance.onboarding.* i18n keys; add balanceLanding.ts + test.
- Add balance.hub.* and balance.landing.* keys in FR and EN.
- CHANGELOG (EN + FR) under [Unreleased].
Resolves#244
