Remove v1 onboarding and rely only on v2 (#22398)

https://github.com/user-attachments/assets/a6bfaac3-6c79-4fd5-999a-e6a70cff8ac8


Removes the old (v1) signup and onboarding flow now that v2 is the only
path, and drops the `isOnboardingV2` flag entirely. The surviving
(formerly-v2) pages reclaim the canonical `AppPath` members and clean
URLs (`/welcome`, `/verify`, `/workspace-activation`, `/create/profile`,
`/sync/emails`, `/install-apps`, `/invite-team`, `/plan-required`).

- Deletes the v1 pages, the v1 workspace-creation form, the
`isOnboardingV2State` flag + `onboardingV2` URL-param plumbing, and
`InstallAppsAutoSkipEffect`.
- Collapses the router and page-change navigation matrix to a single set
of paths, and renames the v2 components/stories to drop the `V2` suffix.

Follow-up fixes so the single flow behaves correctly on every
deployment:

- Restore the captcha-token, query-param and pageview effects on the
default (root) domain, and serve `/authorize` there so OAuth login keeps
working.
- Gate the invite-team → `/plan-required` interception on billing so
billing-disabled instances aren't trapped on the upgrade page.
- On a cold boot to an auth/onboarding path, show the onboarding loader
instead of the CRM skeleton, and add `/verify-email` and
`/plan-required/payment-success` to that loader path list.
- Add a retry to PaymentSuccess after the confirmation timeout, fix the
InstallApps icon crossfade, restyle the book-call pages for the
full-page layout, and delete code orphaned by the v1 removal.
- Extract the pageview/captcha/query-param logic out of
`PageChangeEffect` into standalone Effect components shared by the root
and workspace app trees.

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---------

Co-authored-by: Félix Malfait <felix.malfait@gmail.com>

packages/twenty-front/src/loading/components/UserOrMetadataLoader.tsx

@@ -1,10 +1,7 @@
 import { styled } from '@linaria/react';
 
-import { useShowAuthModal } from '@/ui/layout/hooks/useShowAuthModal';
-import { RootStackingContextZIndices } from '@/ui/layout/constants/RootStackingContextZIndices';
 import { NAVIGATION_DRAWER_CONSTRAINTS } from '@/ui/layout/resizable-panel/constants/NavigationDrawerConstraints';
 import { MOBILE_VIEWPORT, themeCssVariables } from 'twenty-ui/theme-constants';
-import { ModalBackdrop } from 'twenty-ui/surfaces';
 import { LeftPanelSkeletonLoader } from '~/loading/components/LeftPanelSkeletonLoader';
 import { PageContentSkeletonLoader } from '~/loading/components/PageContentSkeletonLoader';
 
@@ -28,16 +25,8 @@ const StyledLeftPanelWrapper = styled.div`
 `;
 
 export const UserOrMetadataLoader = () => {
-  const showAuthModal = useShowAuthModal();
-
   return (
     <StyledContainer>
-      {showAuthModal && (
-        <ModalBackdrop
-          overlay="dark"
-          backdropZIndex={RootStackingContextZIndices.RootModalBackDrop}
-        />
-      )}
       <StyledLeftPanelWrapper>
         <LeftPanelSkeletonLoader />
       </StyledLeftPanelWrapper>