feat: in-app update downloader with progress, Gitea auto-push hook

- update_checker: Gitea at git.steggi-matrix.work, Windows + Android support, asset URL detection
- update_download_dialog: animated Pyramid logo, progress bar, platform install (exe/apk)
- update_banner: Herunterladen button triggers dialog, dismiss option
- Android: REQUEST_INSTALL_PACKAGES permission + FileProvider for APK install
- post-commit hook: auto-push to Gitea on every commit
- chat_input: larger send button (60px desktop), more padding, bigger icon
- rooms_panel: space menu visible on mobile (leave space fix)
- docs: feature-checklist.md added

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/features/chat/chat_input.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:matrix/matrix.dart';
@@ -53,6 +54,10 @@ class _ChatInputState extends State<ChatInput> {
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
+    final isDesktop = !kIsWeb &&
+        (defaultTargetPlatform == TargetPlatform.windows ||
+            defaultTargetPlatform == TargetPlatform.linux ||
+            defaultTargetPlatform == TargetPlatform.macOS);
 
     return SafeArea(
       child: Column(
@@ -63,7 +68,12 @@ class _ChatInputState extends State<ChatInput> {
             onClear: widget.onClearReply ?? () {},
           ),
           Padding(
-            padding: const EdgeInsets.fromLTRB(8, 4, 8, 8),
+            padding: EdgeInsets.fromLTRB(
+              isDesktop ? 12 : 8,
+              isDesktop ? 10 : 4,
+              isDesktop ? 12 : 8,
+              isDesktop ? 14 : 8,
+            ),
             child: Row(
               crossAxisAlignment: CrossAxisAlignment.end,
               children: [
@@ -73,14 +83,19 @@ class _ChatInputState extends State<ChatInput> {
                     minLines: 1,
                     maxLines: 6,
                     textCapitalization: TextCapitalization.sentences,
+                    style: TextStyle(fontSize: isDesktop ? 16 : 14),
                     decoration: InputDecoration(
                       hintText: 'Nachricht...',
-                      contentPadding: const EdgeInsets.symmetric(
-                        horizontal: 16,
-                        vertical: 10,
+                      hintStyle: TextStyle(
+                        fontSize: isDesktop ? 16 : 14,
+                        color: theme.colorScheme.onSurface.withAlpha(100),
+                      ),
+                      contentPadding: EdgeInsets.symmetric(
+                        horizontal: isDesktop ? 22 : 16,
+                        vertical: isDesktop ? 20 : 10,
                       ),
                       border: OutlineInputBorder(
-                        borderRadius: BorderRadius.circular(24),
+                        borderRadius: BorderRadius.circular(isDesktop ? 16 : 24),
                         borderSide: BorderSide.none,
                       ),
                       filled: true,
@@ -89,19 +104,30 @@ class _ChatInputState extends State<ChatInput> {
                     onSubmitted: (_) => _send(),
                     keyboardType: TextInputType.multiline,
                     inputFormatters: [
-                      // Shift+Enter = newline, Enter = send
                       _SendOnEnterFormatter(onSend: _send),
                     ],
                   ),
                 ),
-                const SizedBox(width: 8),
-                AnimatedScale(
-                  scale: _canSend ? 1.0 : 0.8,
-                  duration: const Duration(milliseconds: 150),
-                  child: FloatingActionButton.small(
-                    onPressed: _canSend ? _send : null,
-                    elevation: _canSend ? 2 : 0,
-                    child: const Icon(Icons.send_rounded),
+                SizedBox(width: isDesktop ? 10 : 8),
+                GestureDetector(
+                  onTap: _canSend ? _send : null,
+                  child: AnimatedContainer(
+                    duration: const Duration(milliseconds: 150),
+                    width: isDesktop ? 60 : 44,
+                    height: isDesktop ? 60 : 44,
+                    decoration: BoxDecoration(
+                      color: _canSend
+                          ? theme.colorScheme.primary
+                          : theme.colorScheme.primary.withAlpha(70),
+                      borderRadius: BorderRadius.circular(isDesktop ? 16 : 14),
+                    ),
+                    child: Center(
+                      child: Icon(
+                        Icons.send_rounded,
+                        size: isDesktop ? 26 : 20,
+                        color: Colors.white,
+                      ),
+                    ),
                   ),
                 ),
               ],