feat: integrate user profile pictures with circular avatar display and upload in settings

frontend/src/components/UnifiedShareModal.tsx

@@ -10,6 +10,7 @@ import {
 } from 'lucide-react';
 import { User, Team, UnifiedShare } from '../lib/types';
 import { UserAutocomplete } from '../features/UserAutocomplete';
+import { UserAvatar } from './UserAvatar';
 
 export interface UnifiedShareModalProps {
   isOpen: boolean;
@@ -284,15 +285,18 @@ export const UnifiedShareModal: React.FC<UnifiedShareModalProps> = ({
                     className="p-2.5 bg-canvas border border-border rounded-btn flex items-center justify-between gap-3 text-xs hover:border-border/80 transition-colors"
                   >
                     <div className="flex items-center gap-2.5 min-w-0">
-                      <div
-                        className={`w-7 h-7 rounded-btn flex items-center justify-center shrink-0 ${
-                          isTeam
-                            ? 'bg-accent/15 text-accent'
-                            : 'bg-surface-2 text-main border border-border'
-                        }`}
-                      >
-                        {isTeam ? <Users className="w-3.5 h-3.5" /> : <UserIcon className="w-3.5 h-3.5" />}
-                      </div>
+                      {isTeam ? (
+                        <div className="w-7 h-7 rounded-full flex items-center justify-center shrink-0 bg-accent/15 text-accent border border-accent/25">
+                          <Users className="w-3.5 h-3.5" />
+                        </div>
+                      ) : (
+                        <UserAvatar
+                          avatarUrl={sh.avatarUrl || collaborators.find((c) => c.id === sh.targetId)?.avatarUrl}
+                          name={sh.targetName || sh.targetEmail}
+                          size="sm"
+                          className="border border-border/80"
+                        />
+                      )}
                       <div className="truncate">
                         <div className="font-medium text-main truncate flex items-center gap-1.5">
                           <span className="truncate">{sh.targetName || (isTeam ? 'Gruppe' : sh.targetEmail || 'Benutzer')}</span>

frontend/src/components/UserAvatar.tsx

@@ -0,0 +1,157 @@
+import React, { useState } from 'react';
+
+export interface UserAvatarProps {
+  user?: {
+    displayName?: string;
+    email?: string;
+    avatarUrl?: string;
+  } | null;
+  name?: string;
+  avatarUrl?: string;
+  size?: 'xs' | 'sm' | 'md' | 'lg' | 'xl';
+  className?: string;
+  alt?: string;
+}
+
+const SIZE_MAP = {
+  xs: 'w-5 h-5 text-[10px]',
+  sm: 'w-7 h-7 text-xs',
+  md: 'w-9 h-9 text-sm',
+  lg: 'w-12 h-12 text-base',
+  xl: 'w-20 h-20 text-2xl',
+};
+
+const BG_COLORS = [
+  'bg-primary/20 text-primary border-primary/30',
+  'bg-secondary/20 text-secondary border-secondary/30',
+  'bg-accent/20 text-accent border-accent/30',
+  'bg-info/20 text-info border-info/30',
+  'bg-success/20 text-success border-success/30',
+  'bg-warning/20 text-warning border-warning/30',
+];
+
+function getInitials(name?: string, email?: string): string {
+  const cleanName = (name || '').trim();
+  if (cleanName) {
+    const parts = cleanName.split(/\s+/);
+    if (parts.length >= 2) {
+      return (parts[0][0] + parts[1][0]).toUpperCase();
+    }
+    return cleanName.slice(0, 2).toUpperCase();
+  }
+  const cleanEmail = (email || '').trim();
+  if (cleanEmail) {
+    return cleanEmail.slice(0, 2).toUpperCase();
+  }
+  return '?';
+}
+
+function getColorIndex(str: string): number {
+  let hash = 0;
+  for (let i = 0; i < str.length; i++) {
+    hash = str.charCodeAt(i) + ((hash << 5) - hash);
+  }
+  return Math.abs(hash) % BG_COLORS.length;
+}
+
+export function isEmoji(str?: string): boolean {
+  if (!str) return false;
+  const trimmed = str.trim();
+  // Simple heuristic: length <= 8 and not a URL or base64 image
+  return !trimmed.startsWith('data:') && !trimmed.startsWith('http') && !trimmed.startsWith('/') && trimmed.length <= 8;
+}
+
+export const UserAvatar: React.FC<UserAvatarProps> = ({
+  user,
+  name,
+  avatarUrl,
+  size = 'md',
+  className = '',
+  alt,
+}) => {
+  const [imageError, setImageError] = useState(false);
+
+  const effectiveAvatarUrl = avatarUrl !== undefined ? avatarUrl : user?.avatarUrl;
+  const effectiveName = name !== undefined ? name : (user?.displayName || user?.email || '');
+  const effectiveEmail = user?.email || '';
+
+  const sizeClass = SIZE_MAP[size] || SIZE_MAP.md;
+  const initials = getInitials(effectiveName, effectiveEmail);
+  const colorIndex = getColorIndex(effectiveName || effectiveEmail || 'user');
+  const colorClass = BG_COLORS[colorIndex];
+
+  const hasImage = Boolean(
+    effectiveAvatarUrl &&
+    !imageError &&
+    (effectiveAvatarUrl.startsWith('data:image/') ||
+     effectiveAvatarUrl.startsWith('http://') ||
+     effectiveAvatarUrl.startsWith('https://') ||
+     effectiveAvatarUrl.startsWith('/'))
+  );
+
+  const isEmojiAvatar = Boolean(effectiveAvatarUrl && isEmoji(effectiveAvatarUrl));
+
+  return (
+    <div
+      className={`inline-flex items-center justify-center rounded-full aspect-square shrink-0 select-none overflow-hidden font-semibold transition-all ${sizeClass} ${className}`}
+      title={effectiveName || alt}
+    >
+      {hasImage ? (
+        <img
+          src={effectiveAvatarUrl}
+          alt={alt || effectiveName || 'Avatar'}
+          onError={() => setImageError(true)}
+          className="w-full h-full object-cover rounded-full"
+        />
+      ) : isEmojiAvatar ? (
+        <div className="w-full h-full flex items-center justify-center bg-base-300/80 rounded-full">
+          <span className="leading-none">{effectiveAvatarUrl}</span>
+        </div>
+      ) : (
+        <div className={`w-full h-full flex items-center justify-center rounded-full border ${colorClass}`}>
+          <span className="leading-none tracking-tight">{initials}</span>
+        </div>
+      )}
+    </div>
+  );
+};
+
+/**
+ * Resizes and center-crops an uploaded image file to a compact base64 Data URL.
+ */
+export async function resizeImageToDataUrl(file: File, maxSize = 256): Promise<string> {
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader();
+    reader.onerror = () => reject(new Error('Fehler beim Lesen der Datei'));
+    reader.onload = (e) => {
+      const img = new Image();
+      img.onerror = () => reject(new Error('Fehler beim Laden des Bildes'));
+      img.onload = () => {
+        const canvas = document.createElement('canvas');
+        canvas.width = maxSize;
+        canvas.height = maxSize;
+        const ctx = canvas.getContext('2d');
+        if (!ctx) {
+          reject(new Error('Canvas Context konnte nicht erstellt werden'));
+          return;
+        }
+
+        // Center crop calculation
+        const minDim = Math.min(img.width, img.height);
+        const sx = (img.width - minDim) / 2;
+        const sy = (img.height - minDim) / 2;
+
+        ctx.drawImage(img, sx, sy, minDim, minDim, 0, 0, maxSize, maxSize);
+
+        // Try webp first, fallback to jpeg
+        let dataUrl = canvas.toDataURL('image/webp', 0.85);
+        if (!dataUrl.startsWith('data:image/webp')) {
+          dataUrl = canvas.toDataURL('image/jpeg', 0.85);
+        }
+        resolve(dataUrl);
+      };
+      img.src = e.target?.result as string;
+    };
+    reader.readAsDataURL(file);
+  });
+}