## Summary
- Removes the `account-mapping` Pennant feature flag entirely, making
the account mapping flow (pending accounts data + map-accounts page) the
default and only code path
- Removes the old direct-creation branches from all banking controllers
(Authorization, Bitpanda, Binance, IndexaCapital)
- Extracts a shared `CreatesAccountsFromPending` trait for the
onboarding auto-create logic
- Updates all controller tests to reflect the always-on mapping behavior
## Changes
### Backend
- **AppServiceProvider** — removed `account-mapping` flag definition
- **AuthorizationController** — removed flag check +
`createAccountsFromSession()` dead code; always stores
`pending_accounts_data` and redirects to mapping
- **BitpandaController / BinanceController / IndexaCapitalController** —
removed flag checks, old inline account creation, and unused imports
- **HandleInertiaRequests / ActivateDevelopmentFeatures /
ResolvesFeatures** — removed `account-mapping` from flag arrays
- **New `CreatesAccountsFromPending` trait** — shared auto-create logic
for onboarding path (to be consumed next)
### Frontend
- Removed `'account-mapping'` from the TypeScript `Features` interface
### Tests
- Merged flag-specific test variants into single always-on tests
- Removed redundant tests that tested the old disabled-flag code path
- Updated assertions to check `pending_accounts_data` instead of direct
account creation
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