Surface driver login on /login and /; make SubuserLogin responsive (#265)

## Why

Drivers (sub-users) could only reach `/login/driver` via the direct URL
— there was no UI affordance anywhere else. They had to know the URL or
be sent a link by their admin. Mobile / tablet users had no obvious path
to the driver login either.

## What changed

- `src/components/forms/auth/LoginForm.vue` — Add a clearly-clickable
**Driver login** button below the existing "Login with QR code" link.
Distinct color (`#1584BC`) and a truck icon separate it from the primary
customer login. Test ID `driver-login-link`, ID `driver-login-button`.
The button is reachable on every viewport (44px+ touch target, no
horizontal scroll on mobile).
- `src/views/pages/LandingPage.vue` — Add a secondary **driver entry**
block below the customer login form, in a tinted container (`#F2F8FC`
with `#BFE0EF` border) with the intro "Are you a driver? Log in here to
register a wash." Test ID `landing-driver-entry` /
`landing-driver-login-link`.
- `src/views/auth/SubuserLogin.vue` — Make the page responsive:
  - **Desktop (>1024px):** 33%/67% sidebar + main (unchanged).
  - **Tablet (≤1024px):** 25%/75% tighter split, smaller sidebar title.
- **Mobile (≤768px):** Stack the sidebar above main (full-width 140px
header band) so it never forces a horizontal scroll.
- `src/i18n/source/{global/shared,da,en,de,no,sv}/.../auth/index.json` —
Add `auth.driver_login_button` and `auth.driver_entry_intro` in 5
locales. Run `npm run i18n:v2:compile` to regenerate the v2 bundle.
- `tests/e2e/driverAuth.spec.ts` — New E2E suite covering:
  - `/login` shows the driver login button on desktop and mobile.
  - `/` shows the driver entry block.
- Clicking either entry navigates to `/login/driver` and the form is
usable (inputs reachable, submit button visible) on mobile.

## Verification

- `npx eslint` — clean for changed files.
- `npm run i18n:v2:check` — green after `i18n:v2:compile`.

## Caveats

- New `.driver-entry` and `.driver-login-link` styles are scoped to the
components; if a global theme override is required, lift to a shared
SCSS partial in a follow-up.
- The driver login button is placed below the customer login in the
form. On very tall mobile viewports it may sit below the fold; in
practice the form fits in the first scroll, but worth watching in
production analytics.

🤖 Generated with [OpenClaw](https://openclaw.ai)

---------

Co-authored-by: Truck Wash Agent <agent@copenhagentruckwash.local>

src/i18n/generated/en-v2.json

@@ -1972,6 +1972,8 @@
         "auth": {
           "country_code": "@.capitalize:{'words.generated.country'} @.capitalize:{'words.generated.code'}",
           "customer_login_title": "@.capitalize:{'words.generated.customer'} @.capitalize:{'words.generated.login'}",
+          "driver_entry_intro": "@.capitalize:{'words.generated.are'} @:{'words.generated.you'} @:{'words.generated.a'} @:{'words.generated.driver'}? @.capitalize:{'words.generated.log'} @:{'words.generated.in'} @:{'words.generated.here'} @:{'words.generated.to'} @:{'words.generated.register'} @:{'words.generated.a'} @:{'words.generated.wash'}.",
+          "driver_login_button": "@.capitalize:{'words.generated.driver'} @.capitalize:{'words.generated.login'}",
           "driver_login_title": "@.capitalize:{'words.generated.driver'} @.capitalize:{'words.generated.login'}",
           "forgot_password": "Forgot @.capitalize:{'words.generated.password'}",
           "operator_tagline": "@.capitalize:{'words.generated.truckwash'}.@:{'words.generated.io'} - @:{'words.generated.digital'} @:{'words.generated.solutions'} @:{'words.generated.for'} @:{'words.generated.truck'} @:{'words.generated.washing'}",