feat: Mandant/Reseller ohne E-Mail anlegbar (Temp-Passwort statt Einladung)

- admin_email bzw. reseller email optional; ohne E-Mail wird interne Login-
  Kennung (<name>@<slug>.local) + einmaliges Temp-Passwort erzeugt, Account
  sofort aktiv, kein Mailversand
- TenantOut/ResellerOut: initial_password (einmalig) ergänzt
- LoginRequest.email: str statt EmailStr (Kennung muss kein zustellbares
  Postfach sein; .local-Domains sind sonst nicht einloggbar)
- Frontend: E-Mail-Felder optional, CredDialog zeigt Login + Temp-Passwort einmalig
- Test: Anlage ohne E-Mail + Login mit generierten Zugangsdaten; 173/173 grün

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/pages/TenantsPage.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useState } from 'react'
 import { api } from '../api/client'
 import { Layout } from '../components/Layout'
+import { CredDialog } from './ResellerCompaniesPage'
 
 interface Tenant {
   id: string; name: string; slug: string; plan: string; is_active: boolean
@@ -27,6 +28,7 @@ export function TenantsPage() {
   const [showNewReseller, setShowNewReseller] = useState(false)
   const [rForm, setRForm] = useState({ ...emptyReseller })
   const [busy, setBusy] = useState(false)
+  const [cred, setCred] = useState<{ title: string; email: string; password: string } | null>(null)
 
   async function load() {
     try {
@@ -49,10 +51,15 @@ export function TenantsPage() {
     setBusy(true); setError(null)
     try {
       const q = form.reseller_id ? `?reseller_id=${form.reseller_id}` : ''
-      const { reseller_id, ...body } = form
+      const { reseller_id, ...rest } = form
       void reseller_id
-      await api.post(`/admin/tenants${q}`, body)
-      setShowNew(false); setForm({ ...empty, reseller_id: '' }); await load()
+      const body = { ...rest, admin_email: rest.admin_email.trim() || undefined }
+      const res = await api.post<{ initial_password?: string | null; admin_email?: string | null }>(
+        `/admin/tenants${q}`, body,
+      )
+      setShowNew(false); setForm({ ...empty, reseller_id: '' })
+      if (res.initial_password) setCred({ title: 'Zugangsdaten Firmen-Administrator', email: res.admin_email ?? '', password: res.initial_password })
+      await load()
     } catch (e: unknown) {
       setError(e instanceof Error ? e.message : 'Fehler beim Anlegen')
     } finally { setBusy(false) }
@@ -71,8 +78,11 @@ export function TenantsPage() {
   async function createReseller() {
     setBusy(true); setError(null)
     try {
-      await api.post('/admin/resellers', rForm)
-      setShowNewReseller(false); setRForm({ ...emptyReseller }); await load()
+      const body = { ...rForm, email: rForm.email.trim() || undefined }
+      const res = await api.post<{ initial_password?: string | null; email?: string | null }>('/admin/resellers', body)
+      setShowNewReseller(false); setRForm({ ...emptyReseller })
+      if (res.initial_password) setCred({ title: 'Zugangsdaten Reseller', email: res.email ?? '', password: res.initial_password })
+      await load()
     } catch (e: unknown) {
       setError(e instanceof Error ? e.message : 'Fehler beim Anlegen')
     } finally { setBusy(false) }
@@ -204,8 +214,8 @@ export function TenantsPage() {
               </select>
             </Field>
             <hr className="my-1" />
-            <p className="text-xs text-gray-500">Erster Administrator (erhält Einladung per E-Mail):</p>
-            <Field label="Admin E-Mail"><input className={inp} value={form.admin_email} onChange={e => setForm({ ...form, admin_email: e.target.value })} /></Field>
+            <p className="text-xs text-gray-500">Erster Administrator. Mit E-Mail → Einladung; ohne E-Mail → einmaliges Temp-Passwort.</p>
+            <Field label="Admin E-Mail (optional)"><input className={inp} placeholder="leer lassen für Temp-Passwort" value={form.admin_email} onChange={e => setForm({ ...form, admin_email: e.target.value })} /></Field>
             <div className="grid grid-cols-2 gap-3">
               <Field label="Vorname"><input className={inp} value={form.admin_first_name} onChange={e => setForm({ ...form, admin_first_name: e.target.value })} /></Field>
               <Field label="Nachname"><input className={inp} value={form.admin_last_name} onChange={e => setForm({ ...form, admin_last_name: e.target.value })} /></Field>
@@ -215,14 +225,16 @@ export function TenantsPage() {
 
         {showNewReseller && (
           <Modal title="Neuen Reseller anlegen" onClose={() => setShowNewReseller(false)} onSubmit={createReseller} busy={busy}>
-            <p className="text-xs text-gray-500">Der Reseller erhält eine Einladung per E-Mail und kann danach eigene Firmen anlegen und verwalten.</p>
-            <Field label="E-Mail"><input className={inp} value={rForm.email} onChange={e => setRForm({ ...rForm, email: e.target.value })} /></Field>
+            <p className="text-xs text-gray-500">Mit E-Mail erhält der Reseller eine Einladung – ohne E-Mail ein einmaliges Temp-Passwort. Danach kann er eigene Firmen anlegen und verwalten.</p>
+            <Field label="E-Mail (optional)"><input className={inp} placeholder="leer lassen für Temp-Passwort" value={rForm.email} onChange={e => setRForm({ ...rForm, email: e.target.value })} /></Field>
             <div className="grid grid-cols-2 gap-3">
               <Field label="Vorname"><input className={inp} value={rForm.first_name} onChange={e => setRForm({ ...rForm, first_name: e.target.value })} /></Field>
               <Field label="Nachname"><input className={inp} value={rForm.last_name} onChange={e => setRForm({ ...rForm, last_name: e.target.value })} /></Field>
             </div>
           </Modal>
         )}
+
+        {cred && <CredDialog title={cred.title} cred={cred} onClose={() => setCred(null)} />}
       </div>
     </Layout>
   )