feat: implement mobile-responsive tab navigation with select dropdown

- Replace tabs with select dropdown on mobile devices for better UX
- Add responsive Layout.Header for mobile with proper styling
- Implement hybrid CSS approach: static styles in CSS, dynamic in inline
- Add mobile-specific select styling with transparent background
- Remove unused CaretDownOutlined import, use EllipsisOutlined for dropdown
- Optimize mobile header layout with compact zoom controls
- Separate mobile and desktop rendering logic for better maintainability
- Add CSS class for mobile project header with proper positioning

frontend/src/global.css

@@ -13,12 +13,12 @@
     color: #fff;
 }
 
-.ant-tabs > .ant-tabs-nav button.ant-btn-variant-outlined:disabled {
+button.ant-btn-variant-outlined:disabled {
     background: rgba(255, 255, 255, 0.2);
 }
 
-.ant-tabs > .ant-tabs-nav button.ant-tabs-nav-more {
-    color: #fff;
+.ant-tabs-nav button.ant-tabs-nav-more {
+    color: #fff !important;
 }
 
 .ant-layout-header.overview-header {
@@ -41,4 +41,35 @@
     .ant-tabs-content {
         padding: 0px 16px; /* Reduced padding on mobile */
     }
+}
+
+/* Mobile project header */
+.mobile-project-header {
+    padding: 0px 16px !important;
+    position: sticky !important;
+    top: 0 !important;
+    z-index: 100 !important;
+    display: flex !important;
+    align-items: center !important;
+    justify-content: space-between !important;
+    gap: 12px !important;
+    height: auto !important;
+    min-height: 64px !important;
+}
+
+/* Mobile select styling */
+@media (max-width: 768px) {
+    .ant-select .ant-select-selector {
+        background: rgba(255, 255, 255, 0.1) !important;
+        border: 1px solid rgba(255, 255, 255, 0.2) !important;
+        color: #fff !important;
+    }
+    
+    .ant-select .ant-select-selection-item {
+        color: #fff !important;
+    }
+    
+    .ant-select .ant-select-arrow {
+        color: #fff !important;
+    }
 }

frontend/src/pages/ProjectDetail.js

@@ -1,6 +1,6 @@
 import React, { useEffect, useState } from 'react';
 import { useParams, useNavigate } from 'react-router-dom';
-import { Tabs, Button, Spin, Skeleton, Result, Grid } from 'antd';
+import { Tabs, Button, Spin, Skeleton, Result, Grid, Select, Layout } from 'antd';
 import { ArrowLeftOutlined, LoadingOutlined, LockOutlined, MinusOutlined, PlusOutlined, EllipsisOutlined } from '@ant-design/icons';
 import UserMenu from '../components/UserMenu';
 import FilePreview, { formatFileSize, formatDuration } from '../components/FilePreview';
@@ -243,45 +243,93 @@ function ProjectDetail({ user, darkMode, onLogout, onToggleDarkMode, overridePar
     }
   };
 
+  // Finde den aktuellen Tab-Content
+  const activeTabContent = tabs.find(tab => tab.key === activeKey)?.children;
+
   return (
     <div>
       <Spin spinning={loading} indicator={<LoadingOutlined spin />} size="large" tip="Lade Projektdaten..." fullscreen />
       {!loading && (
         tabs.length > 0 ? (
-          <Tabs 
-            items={tabs}
-            more={{ icon: <EllipsisOutlined />, trigger: 'click' }}
-            activeKey={activeKey}
-            onChange={handleTabChange}
-            tabBarExtraContent={{
-              left: (
-                <div style={{ display: 'flex', alignItems: 'center' }}>
+          isMobile ? (
+            // Mobile Darstellung mit Select und separatem Content
+            <Layout>
+              <Layout.Header className="mobile-project-header" style={{
+                background: darkMode ? '#001f1e' : '#001f1e', // Dynamisch, falls später unterschiedliche Themes gewünscht
+                color: darkMode ? '#fff' : '#fff'
+              }}>
+                <div style={{ display: 'flex', alignItems: 'center', gap: 12, flex: 1 }}>
                   <Button
                     icon={<ArrowLeftOutlined style={{ color: '#001f1e' }} />}
                     onClick={() => navigate('/')}
-                    style={{ marginRight: projectLogo ? 12 : 0 }}
+                    size="small"
+                  />
+                  <Select
+                    value={activeKey}
+                    onChange={handleTabChange}
+                    style={{ 
+                      flex: 1,
+                      minWidth: 120,
+                      height: 26
+                    }}
+                    size="middle"
+                    suffixIcon={<EllipsisOutlined style={{ color: '#fff' }} />}
+                    options={tabs.map(tab => ({
+                      value: tab.key,
+                      label: tab.label
+                    }))}
                   />
-                  {projectLogo && !isMobile && (
-                    <img
-                      src={projectLogo}
-                      alt="Logo"
-                      style={{ height: 38, marginRight: 32, objectFit: 'contain' }}
-                    />
-                  )}
                 </div>
-              ),
-              right: (
-                <div style={{ display: 'flex', alignItems: 'center', gap: 12 }}>
-                  <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
+                <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
+                  <div style={{ display: 'flex', alignItems: 'center', gap: 4 }}>
                     <Button size="small" shape="circle" icon={<MinusOutlined style={{ color: '#001f1e' }} />} onClick={() => handleZoom('out')} disabled={zoom <= ZOOM_LEVELS[0]}></Button>
-                    <span style={{ minWidth: 48, textAlign: 'center' }}>{Math.round(zoom * 100)}%</span>
+                    <span style={{ minWidth: 36, textAlign: 'center', fontSize: 12 }}>{Math.round(zoom * 100)}%</span>
                     <Button size="small" shape="circle" icon={<PlusOutlined style={{ color: '#001f1e' }} />} onClick={() => handleZoom('in')} disabled={zoom >= ZOOM_LEVELS[ZOOM_LEVELS.length - 1]}></Button>
                   </div>
                   <UserMenu user={user} onLogout={onLogout} darkMode={darkMode} onToggleDarkMode={onToggleDarkMode} />
                 </div>
-              )
-            }}
-          />
+              </Layout.Header>
+              <Layout.Content style={{ padding: '0px 16px' }}>
+                {activeTabContent}
+              </Layout.Content>
+            </Layout>
+          ) : (
+            // Desktop Darstellung mit Tabs
+            <Tabs 
+              items={tabs}
+              more={{ icon: <EllipsisOutlined />, trigger: 'click' }}
+              activeKey={activeKey}
+              onChange={handleTabChange}
+              tabBarExtraContent={{
+                left: (
+                  <div style={{ display: 'flex', alignItems: 'center' }}>
+                    <Button
+                      icon={<ArrowLeftOutlined style={{ color: '#001f1e' }} />}
+                      onClick={() => navigate('/')}
+                      style={{ marginRight: projectLogo ? 12 : 0 }}
+                    />
+                    {projectLogo && (
+                      <img
+                        src={projectLogo}
+                        alt="Logo"
+                        style={{ height: 38, marginRight: 32, objectFit: 'contain' }}
+                      />
+                    )}
+                  </div>
+                ),
+                right: (
+                  <div style={{ display: 'flex', alignItems: 'center', gap: 12 }}>
+                    <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
+                      <Button size="small" shape="circle" icon={<MinusOutlined style={{ color: '#001f1e' }} />} onClick={() => handleZoom('out')} disabled={zoom <= ZOOM_LEVELS[0]}></Button>
+                      <span style={{ minWidth: 48, textAlign: 'center' }}>{Math.round(zoom * 100)}%</span>
+                      <Button size="small" shape="circle" icon={<PlusOutlined style={{ color: '#001f1e' }} />} onClick={() => handleZoom('in')} disabled={zoom >= ZOOM_LEVELS[ZOOM_LEVELS.length - 1]}></Button>
+                    </div>
+                    <UserMenu user={user} onLogout={onLogout} darkMode={darkMode} onToggleDarkMode={onToggleDarkMode} />
+                  </div>
+                )
+              }}
+            />
+          )
         ) : error ? (
           // Spezifische Fehlerbehandlung
           <Result