style: verbleibende flutter-analyze Deprecations beheben

withOpacity/activeColor/cacheExtent/PublicRoomsChunk durch die neuen
Flutter-3.44-Äquivalente ersetzt.

lib/features/chat/attachment_dialog.dart

@@ -184,7 +184,7 @@ class _AttachmentDialogState extends State<AttachmentDialog> {
                       Switch.adaptive(
                         value: !_compress,
                         onChanged: (v) => setState(() => _compress = !v),
-                        activeColor: pt.accent,
+                        activeThumbColor: pt.accent,
                       ),
                     ],
                   ),

lib/features/chat/chat_view.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:flutter/rendering.dart' show ScrollCacheExtent;
 import 'package:flutter/services.dart' show Clipboard, ClipboardData;
 
 import 'package:desktop_drop/desktop_drop.dart';
@@ -1598,7 +1599,7 @@ class _MessageList extends StatelessWidget {
       reverse: true,
       physics: const ClampingScrollPhysics(),
       padding: const EdgeInsets.only(bottom: 8),
-      cacheExtent: 2500,
+      scrollCacheExtent: const ScrollCacheExtent.pixels(2500),
       itemCount: itemKeys.length,
       findChildIndexCallback: (Key key) {
         // Only return an index when the key still maps to that exact slot —

lib/features/chat/media_player.dart

@@ -266,7 +266,7 @@ class _AArtwork extends StatelessWidget {
         borderRadius: BorderRadius.circular(size * 0.3),
         gradient: LinearGradient(begin: Alignment.topLeft, end: Alignment.bottomRight, colors: [c1, c2]),
       ),
-      child: Icon(Icons.music_note, color: Colors.white.withOpacity(0.85), size: size * 0.48),
+      child: Icon(Icons.music_note, color: Colors.white.withValues(alpha: 0.85), size: size * 0.48),
     );
   }
 }
@@ -603,9 +603,9 @@ class _VCenterPlay extends StatelessWidget {
   Widget build(BuildContext context) => Container(
     width: 56, height: 56,
     decoration: BoxDecoration(
-      color: Colors.white.withOpacity(0.10),
+      color: Colors.white.withValues(alpha: 0.10),
       shape: BoxShape.circle,
-      border: Border.all(color: Colors.white.withOpacity(0.18)),
+      border: Border.all(color: Colors.white.withValues(alpha: 0.18)),
     ),
     child: const Icon(Icons.play_arrow, color: Colors.white, size: 26),
   );
@@ -682,14 +682,14 @@ class _VScrubber extends StatelessWidget {
         milliseconds: (dur.inMilliseconds * (d.localPosition.dx / c.maxWidth).clamp(0.0, 1.0)).round())),
     child: SizedBox(height: 16, child: Stack(alignment: Alignment.centerLeft, children: [
       Container(height: 3, decoration: BoxDecoration(
-          color: Colors.white.withOpacity(0.20), borderRadius: BorderRadius.circular(2))),
+          color: Colors.white.withValues(alpha: 0.20), borderRadius: BorderRadius.circular(2))),
       FractionallySizedBox(widthFactor: progress, child: Container(height: 3,
           decoration: BoxDecoration(color: accent, borderRadius: BorderRadius.circular(2)))),
       Positioned(
         left: c.maxWidth * progress.clamp(0.0, 1.0) - 5,
         child: Container(width: 10, height: 10,
             decoration: BoxDecoration(color: accent, shape: BoxShape.circle,
-                boxShadow: [BoxShadow(color: Colors.black.withOpacity(0.4), blurRadius: 0, spreadRadius: 2)])),
+                boxShadow: [BoxShadow(color: Colors.black.withValues(alpha: 0.4), blurRadius: 0, spreadRadius: 2)])),
       ),
     ])),
   ));
@@ -722,7 +722,7 @@ class _VOverlayBtn extends StatelessWidget {
     onTap: onTap,
     borderRadius: BorderRadius.circular(6),
     child: SizedBox(width: 32, height: 32,
-        child: Icon(icon, size: 17, color: Colors.white.withOpacity(0.85))),
+        child: Icon(icon, size: 17, color: Colors.white.withValues(alpha: 0.85))),
   );
 }
 
@@ -750,7 +750,7 @@ class _VSettingsButton extends StatelessWidget {
     color: const Color(0xF014141A),
     shape: RoundedRectangleBorder(
       borderRadius: BorderRadius.circular(10),
-      side: BorderSide(color: Colors.white.withOpacity(0.1)),
+      side: BorderSide(color: Colors.white.withValues(alpha: 0.1)),
     ),
     itemBuilder: (_) => [PopupMenuItem<void>(
       enabled: false, padding: EdgeInsets.zero,
@@ -761,7 +761,7 @@ class _VSettingsButton extends StatelessWidget {
       ),
     )],
     child: SizedBox(width: 32, height: 32,
-        child: Icon(Icons.settings_outlined, size: 16, color: Colors.white.withOpacity(0.85))),
+        child: Icon(Icons.settings_outlined, size: 16, color: Colors.white.withValues(alpha: 0.85))),
   );
 }
 
@@ -812,7 +812,7 @@ class _VSettingsMenuState extends State<_VSettingsMenu> {
             ]),
           ),
         ),
-        Container(height: 1, color: Colors.white.withOpacity(0.08)),
+        Container(height: 1, color: Colors.white.withValues(alpha: 0.08)),
         if (isSpeed)
           ...widget.speeds.map((s) {
             final lbl = '${s == s.toInt() ? s.toInt() : s}x';