## Summary
Both **Email Handles** and **Emailing Domains** were rendered on the
General workspace settings page, but they're workspace-level *email
infrastructure* (inbound shared addresses + outbound sender
authentication) and don't belong with the workspace name, picture, and
domain config.
- New `SettingsWorkspaceEmail` page at `/settings/email`
- Nav item under **Workspace**, hidden when `IS_EMAIL_GROUP_ENABLED` is
off (and gated by `WORKSPACE` permission)
- Related sub-routes (`email-group/:messageChannelId`,
`emailing-domain/:domainId`, etc.) moved from `general/` to `email/` so
the URL space stays consistent with the page
- General page now only contains name, picture, workspace domain, and
the delete-workspace section
No behavior changes to the underlying section components — they're
imported as-is into the new page.
## Test plan
- [ ] With `IS_EMAIL_GROUP_ENABLED` enabled: **Email** appears in the
Workspace nav and the page renders both sections
- [ ] With the flag disabled: **Email** is hidden from nav; navigating
to `/settings/email` directly renders nothing
- [ ] General page no longer shows Email Handles / Emailing Domains
- [ ] Clicking a shared inbox row navigates to
`/settings/email/email-group/:id` (was `general/...`)
- [ ] "Add emailing domain" navigates to
`/settings/email/emailing-domain/new`
## Notes
- Pre-existing `twenty-front` typecheck error in
`FrontComponentRendererProvider.tsx` (React types mismatch between
sibling packages) reproduces on `main` and is unrelated to this PR.
