feat(aether): initial commit – self-hosted Cloud, Phasen 1–7

Go-Backend (chi, pgx, golang-migrate) + React/TS-Frontend als PWA.
Enthalten: Auth inkl. OIDC, Dateien mit Versionen und Papierkorb,
Freigaben (Links + intern), WebDAV, Gruppenordner, Admin/Theming,
Volltextsuche mit OCR, eigener PDF-Betrachter und WOPI-Office
(Collabora/OnlyOffice).

Nicht im Repo: deploy/.env (Sitzungsschlüssel, DB- und Admin-Passwort)
sowie alle Daten- und Build-Verzeichnisse – siehe .gitignore.

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

frontend/src/components/Dialog.tsx

@@ -0,0 +1,66 @@
+import { type FormEvent, useEffect, useRef } from 'react'
+import { useOverlayDismiss } from '../hooks/useOverlayDismiss'
+
+interface Props {
+  title: string
+  defaultValue?: string
+  placeholder?: string
+  confirmLabel?: string
+  onConfirm: (value: string) => void
+  onCancel: () => void
+}
+
+export default function InputDialog({ title, defaultValue = '', placeholder, confirmLabel = 'OK', onConfirm, onCancel }: Props) {
+  const inputRef = useRef<HTMLInputElement>(null)
+  const overlay = useOverlayDismiss(onCancel)
+
+  useEffect(() => {
+    inputRef.current?.focus()
+    inputRef.current?.select()
+  }, [])
+
+  function handleSubmit(e: FormEvent) {
+    e.preventDefault()
+    const val = inputRef.current?.value.trim()
+    if (val) onConfirm(val)
+  }
+
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center p-4"
+         style={{ background: 'rgba(0,0,0,0.6)' }}
+         {...overlay}>
+      <div className="w-full max-w-sm rounded-xl p-5 shadow-2xl border"
+           style={{ background: 'var(--color-surface)', borderColor: 'var(--color-border)' }}>
+        <h2 className="font-semibold mb-4" style={{ color: 'var(--color-text)' }}>{title}</h2>
+        <form onSubmit={handleSubmit} className="space-y-3">
+          <input
+            ref={inputRef}
+            type="text"
+            defaultValue={defaultValue}
+            placeholder={placeholder}
+            className="w-full rounded-lg px-3 py-2.5 text-sm outline-none"
+            style={{
+              background: 'var(--color-surface-2)',
+              border: '1px solid var(--color-border)',
+              color: 'var(--color-text)',
+            }}
+            onFocus={e => e.currentTarget.style.borderColor = 'var(--color-primary)'}
+            onBlur={e => e.currentTarget.style.borderColor = 'var(--color-border)'}
+          />
+          <div className="flex justify-end gap-2">
+            <button type="button" onClick={onCancel}
+                    className="px-4 py-2 text-sm rounded-lg transition-opacity hover:opacity-70"
+                    style={{ color: 'var(--color-text-muted)' }}>
+              Cancel
+            </button>
+            <button type="submit"
+                    className="px-4 py-2 text-sm rounded-lg font-medium"
+                    style={{ background: 'var(--color-primary)', color: 'var(--color-primary-fg)' }}>
+              {confirmLabel}
+            </button>
+          </div>
+        </form>
+      </div>
+    </div>
+  )
+}