The website architecture has been refactored for the internal users and
admins with [1].
Now, they can access the website in the backend inside the website app.
Long story short, the website will be displayed in an iframe in a client
action. The URL of the browser will be tweaked to reflect the iframe one
instead of the real one (which is something like /web#action=..).
It had a few drawbacks:
- On page refresh (F5 or browser button), the user would land on the
frontend version of the website instead of remaining in the backend.
- When the user edited the URL (Like removing `/shop` and typing `/jobs`
instead, he would land on the frontend version too.
- Impossible to directly go to the backend version of the website.
Those are improved with this commit by using a slightly different URL
when we are in the backend. A `/@/` will prefix the iframe URL.
If logged in, the user will land on the backend. If not, it will simply
redirect to the frontend version of the website.
[1]: https://github.com/odoo/odoo/commit/31cc10b91dc7762e23b4bde9b945be0c4ce3fe3b
task-2687506
closesodoo/odoo#94580
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>