## What kind of change does this PR introduce?
Bug fix. Follow-up to #41041 and DEPR-318.
## What is the current behavior?
Marketing "Start your project" links go to `/dashboard`, which redirects
unauthenticated users to `/org` and sets `returnTo=/org`. That value
survives when they switch from sign-in to sign-up, so email verification
still lands on the org list instead of org creation.
## What is the new behavior?
- Sign-in's **Sign up** link rewrites `returnTo=/org` (and
`/organizations`) to `/new`
- Docs mobile menu, www homepage/product CTAs, and solution page CTAs
link to `/dashboard/sign-up` for guests
- Signed-in visitors get the dashboard URL instead, so they never hit
the sign-up form
- Shared `DASHBOARD_SIGN_UP_URL` / `getDashboardCtaHref` helpers for www
Stacked on #41041.
## To test
Stacked on #41041. The studio preview below includes both PRs. www and
docs have their own previews.
### Studio: sign-in → sign-up rewrite
Using the [studio-staging
preview](https://studio-staging-git-dnywh-fixonboarding-return-to-supabase.vercel.app/)
from Vercel checks:
1. Open the preview while logged out. It should land on
`/dashboard/sign-in?returnTo=%2Forg`
2. Click **Sign up**. Expect the URL to include `returnTo=%2Fnew`
### Optional: www CTAs
Using the [www
preview](https://zone-www-dot-com-git-dnywh-fixonboarding-return-to-supabase.vercel.app/):
3. Logged out: homepage, product, or solutions **Start your project**
should go to `/dashboard/sign-up`
4. Logged in: the same CTAs should go to `/dashboard` (not sign-up)
(thought this will be hard if not impossible to test on staging)
### Optional: docs CTAs
Using the [docs
preview](https://docs-git-dnywh-fixonboarding-return-to-supabase.vercel.app/):
5. On mobile nav while logged out, click **Start your project**. Expect
`/dashboard/sign-up`
### Compare on supabase.green
Optional. Just to show what happens currently on `master`:
6. Open **supabase.green** while logged out, then click **Sign up** from
`/dashboard/sign-in?returnTo=%2Forg`. `returnTo` should stay as `/org`
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Start-project and sign-up links now direct visitors to registration
while signed-in users continue to reach the dashboard.
* Homepage, product, solution, and mobile navigation CTAs now provide
consistent authentication-aware destinations.
* Sign-up links preserve return destinations and existing navigation
parameters.
* **Bug Fixes**
* Corrected mobile navigation and marketing CTA links that previously
sent visitors to the dashboard root instead of the appropriate sign-up
flow.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
