Settings: fold Users and Organization into the Settings tabs

The left rail is back to the three places you actually go — Garage,
Charging, Settings — and user management moves inside Settings as an
admin-only tab, next to a new Organization tab that used to be a card
buried in the personal settings. Tab order is Personal settings, Users,
Organization, Integrations. /admin redirects to /settings?tab=users so
old links keep working, and ?tab= picks the starting tab in general.

AdminUsers moves from views/ to components/ since it is a panel now, not
a route, and its page header becomes a section header like its
neighbours. The personal panel was split in two around the integrations
markup, which left no gap between the Profile and Privacy cards; it is
one block again.

Creating a user gets an organization picker for superadmins, defaulting
to "no organization" so an org-less account stays a deliberate choice.
Admins see no picker: the server pins their members to their own org
regardless, which users_test.go now covers along with both superadmin
paths.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Web App/README.md

@@ -21,7 +21,7 @@ server/           Go BFF: embeds web/dist, proxies /api -> API_BASE
 web/              Vue 3 + Vite + Tailwind v4 source
   src/
     main.js         app bootstrap
-    router.js       /login, / (dashboard), /charging, /cars/:id, /settings, /admin
+    router.js       /login, / (dashboard), /charging, /cars/:id, /settings
     api.js          the only place that calls the API Server (base URL resolution)
     auth.js         token/profile state, isAdmin
     prefs.js        theme/locale/date/font preferences -> <html>
@@ -29,12 +29,12 @@ web/              Vue 3 + Vite + Tailwind v4 source
     lib/format.js   date/km formatting + next-service status badges
     lib/attachment.js  upload / fetch / open a record's attached file
     style.css       Tailwind v4 entry (+ dark custom-variant)
-    App.vue         layout shell + nav (Charging + Admin links when relevant)
+    App.vue         layout shell + nav (Garage, Charging, Settings)
     components/     Modal, AttachmentField, CarFormModal, ServiceFormModal,
                     TechnicalCheckFormModal, MaintenanceFormModal, FuelFormModal,
                     DocumentFormModal, ReminderFormModal, PartFormModal, ShareModal,
-                    OrgManager, Logo
-    views/          Login, Dashboard, CarDetail, Charging, Settings, AdminUsers
+                    OrgManager, AdminUsers, Logo
+    views/          Login, Dashboard, CarDetail, Charging, Settings
 ```
 
 ## Requirements
@@ -116,13 +116,14 @@ Config (`server/.env`, copy from `.env.example`):
 - **Charging** — the EV charging screen for connected Anker Solix chargers:
   live status and, in own/proxy control mode, start/stop and charge-limit
   controls driven by the API Server's OCPP Central System.
-- **Settings** — split into tabs: account (name / email verification / password),
-  appearance (theme light/dark/system, locale, date format, currency, font size),
-  profile (avatar, bio), **integrations** (Toyota, Anker Solix), **organization**
-  (create your own — which makes you its admin — or rename/delete the one you
-  administer), data **export/import**, and the account-deletion state machine.
-- **Admin** — `/admin` user management (list / create / role / reset password /
-  delete), gated by the admin role via a router guard + nav link.
+- **Settings** — split into tabs: *Personal settings* — account (name / email
+  verification / password), appearance (theme light/dark/system, locale, date
+  format, currency, font size), profile (avatar, bio), data **export/import**,
+  and the account-deletion state machine; *Integrations* (Toyota, Anker Solix);
+  *Users* for admins; and *Organization* (create your own — which makes you its
+  admin — or rename/delete the one you administer).
+- **Users** — user management (list / create / role / reset password / delete)
+  as the admin-only Settings tab; `/admin` redirects there for old links.
 - **Theming** — light/dark/system app-wide (Tailwind v4 class strategy); `prefs.js`
   toggles `.dark` on `<html>` and applies the saved theme/locale/date/font.