issue#130- Update login attribution to Maintained by Open Source Kigali

[aashishrajdev]

Summary

The auth pages attributed the project to "Open Source Kigali". They now read
"Maintained by Open Source Kigali", and the attribution renders at every
breakpoint instead of desktop only.

The mobile gap

The attribution lived in the brand <aside>, which is hidden ... lg:flex — so
below lg that element is not in the tree at all and mobile showed no
attribution. Satisfying "visible and readable on desktop and mobile layouts"
needed more than a string change:

• MAINTAINER_ATTRIBUTION holds the wording in one place
• the aside footer renders it on desktop
• a new lg:hidden line below the form card renders it on mobile

LoginPage and SetupPage both render through AuthLayout, so both pick this
up without a second copy of the string.

The mobile placement mirrors the compact brand row already in the same file,
which uses lg:hidden for exactly this desktop/mobile split.

Acceptance criteria

• Login page displays "Maintained by Open Source Kigali"
• Setup page shares the layout, so wording is identical
• Visible and readable on desktop and mobile
• Product name "DockSight" unchanged
• No mock data or authentication behavior changed — one presentational file

Testing

• npm run lint — no new warnings (3 pre-existing in ErrorBoundary.tsx,
  button.tsx, ToastProvider.tsx)
• npm test — 44 passed across 3 files
• npm run build — tsc -b && vite build clean
• Manual: /login and /setup, above and below the lg breakpoint

On the test criterion

The issue asks for a focused test if the auth layout is covered by tests. It
isn't — the existing suites are lib/format.test.ts, lib/metrics.test.ts, and
stores/auth.test.ts, all pure logic. There's no @testing-library/react, no
jsdom/happy-dom, and no test block in vite.config.ts. Standing up component
testing felt outside this issue's "frontend branding only" scope, so I left it
out deliberately. Happy to add that infrastructure in a separate PR if you want
AuthLayout covered.

Closes #130