fix(frontend): unify modal focus traps, guard confirmation backdrops, dedupe routes

[trinnode]

Summary

Resolves four frontend accessibility/maintenance issues in one pass.

#1620 — Confirmation modal backdrop + a11y

• ConfirmationModal and WithdrawalConfirmationModal now use the shared useFocusTrap hook instead of ad-hoc focus handling.
• Backdrop clicks and Escape are ignored while isProcessing is true, so a transaction can't be dismissed mid-flight.
• Both dialogs expose role="dialog", aria-modal, aria-labelledby and aria-describedby, and all copy/labels go through t().
• Tests cover open/close, Escape, backdrop clicks (idle + processing), focus-into-dialog, focus restore, and Tab wrapping.

#1621 — One focus trap for every modal surface

• Drawer adopts useFocusTrap, so focus is restored on close and unmount (previously it could be lost on unmount).
• ToastCenter closes on Escape, moves focus into the panel on open, and is configured as a non-modal popover (trapTab: false, lockScroll: false) so Tab can still leave it and page scroll is untouched.
• useFocusTrap gains optional trapTab / lockScroll options (backward compatible — defaults preserve existing behavior).

#1629 — Remove stale tracked artifacts

• Deleted 11 committed build/test artifacts (bundle-stats.html, lint-output*.txt, test-output.txt, test-results.txt, test_output.json, vitest-results*.json).
• Extended frontend/.gitignore and documented the generated reports in frontend/README.md.

#1564 — Deduplicate route definitions

• Removed a duplicate generic ErrorBoundary block and a duplicate /admin route in App.tsx.
• Wrapped the wildcard route in RouteErrorBoundary routeName="not-found".
• Added a route-table smoke test asserting each path deep-links to exactly one route.

CI plumbing

• Repaired the invalid root package.json (duplicate "test" key + trailing comma) that caused a JSON parse failure and blocked the frontend env-validation/version gates.

Test plan

• npm run lint — clean for all touched files
• npx vitest run on the new/updated suites — 48 passing
• Full suite: only pre-existing failures remain (unrelated files: SessionExpiryWarning, VaultDashboard, VirtualizedDataTable, ToastContext, optimisticVaultCache, vaultHealthApi, Portfolio, TransactionHistory, network-banner-stack); all were confirmed failing on main before this branch.

Closes #1620
Closes #1621
Closes #1629
Closes #1564

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[trinnode]

Grouped these four issues since they all touch the same modal/route surfaces, so one review pass covers them.

Notes for review:

• useFocusTrap keeps its existing defaults; the new trapTab / lockScroll flags are opt-in. ToastCenter is the only caller passing them, which is what makes it a non-modal popover (Tab can leave, page scroll is untouched).
• The confirmation modals still fully block dismissal while isProcessing — backdrop clicks and Escape are no-ops in that state, so an in-flight deposit/withdraw can't be closed by accident.
• Drawer moved to the shared hook, which also fixes the case where focus was lost when the drawer unmounted rather than closed.
• The root package.json had a duplicate test key plus a trailing comma, so JSON.parse threw and took down the pnpm-version gate and the frontend env-validation job before anything else could run. Fixed here.

The failing checks that remain on this repo (backend, Rust/CodeQL, coverage-threshold, dependency scans, plus a handful of pre-existing frontend test failures) are unrelated to these files — I confirmed they fail on main too.