feat(02-04): create template picker bottom sheet with German localization

- Add TemplatePickerSheet StatefulWidget with checklist UI for task templates
- Add showTemplatePickerSheet helper for modal display with DraggableScrollableSheet
- Add 4 German localization keys: templatePickerTitle, Skip, Add, Selected count
- All templates unchecked by default, confirm button only enabled with selection

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

lib/features/templates/presentation/template_picker_sheet.dart

@@ -0,0 +1,198 @@
+import 'package:flutter/material.dart';
+
+import 'package:household_keeper/features/tasks/domain/effort_level.dart';
+import 'package:household_keeper/features/tasks/domain/frequency.dart';
+import 'package:household_keeper/features/templates/data/task_templates.dart';
+import 'package:household_keeper/l10n/app_localizations.dart';
+
+/// Bottom sheet with a checklist of task templates for a detected room type.
+///
+/// Displays German-language task templates with frequency and effort labels.
+/// All templates start unchecked. The user can select desired templates and
+/// confirm, or skip (dismiss) without selecting any.
+class TemplatePickerSheet extends StatefulWidget {
+  const TemplatePickerSheet({
+    super.key,
+    required this.roomType,
+    required this.templates,
+    required this.onConfirm,
+  });
+
+  /// The detected room type key (e.g. "kueche").
+  final String roomType;
+
+  /// The template list for this room type.
+  final List<TaskTemplate> templates;
+
+  /// Callback invoked with the selected templates when user confirms.
+  final void Function(List<TaskTemplate> selected) onConfirm;
+
+  @override
+  State<TemplatePickerSheet> createState() => _TemplatePickerSheetState();
+}
+
+class _TemplatePickerSheetState extends State<TemplatePickerSheet> {
+  /// Tracks which template indices are checked.
+  final Set<int> _selected = {};
+
+  /// Display name for the detected room type (first letter capitalized).
+  String get _roomTypeDisplayName {
+    final key = widget.roomType;
+    if (key.isEmpty) return key;
+    return key[0].toUpperCase() + key.substring(1);
+  }
+
+  /// German label combining frequency and effort for a template.
+  String _templateSubtitle(TaskTemplate template) {
+    final freq = FrequencyInterval(
+      intervalType: template.intervalType,
+      days: template.intervalDays,
+    ).label();
+    final effort = template.effortLevel.label();
+    return '$freq \u00b7 $effort';
+  }
+
+  void _onConfirmPressed() {
+    final selectedTemplates = _selected
+        .map((index) => widget.templates[index])
+        .toList(growable: false);
+    widget.onConfirm(selectedTemplates);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = AppLocalizations.of(context);
+    final theme = Theme.of(context);
+
+    return DraggableScrollableSheet(
+      initialChildSize: 0.6,
+      minChildSize: 0.3,
+      maxChildSize: 0.9,
+      expand: false,
+      builder: (context, scrollController) {
+        return Column(
+          children: [
+            // Drag handle
+            Padding(
+              padding: const EdgeInsets.only(top: 12, bottom: 4),
+              child: Container(
+                width: 32,
+                height: 4,
+                decoration: BoxDecoration(
+                  color: theme.colorScheme.onSurfaceVariant.withValues(alpha: 0.4),
+                  borderRadius: BorderRadius.circular(2),
+                ),
+              ),
+            ),
+            // Title and subtitle
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text(
+                    l10n.templatePickerTitle,
+                    style: theme.textTheme.titleLarge,
+                  ),
+                  const SizedBox(height: 4),
+                  Text(
+                    _roomTypeDisplayName,
+                    style: theme.textTheme.bodyMedium?.copyWith(
+                      color: theme.colorScheme.onSurfaceVariant,
+                    ),
+                  ),
+                ],
+              ),
+            ),
+            const Divider(height: 1),
+            // Template checklist
+            Expanded(
+              child: ListView.builder(
+                controller: scrollController,
+                itemCount: widget.templates.length,
+                itemBuilder: (context, index) {
+                  final template = widget.templates[index];
+                  final isChecked = _selected.contains(index);
+                  return CheckboxListTile(
+                    value: isChecked,
+                    onChanged: (checked) {
+                      setState(() {
+                        if (checked == true) {
+                          _selected.add(index);
+                        } else {
+                          _selected.remove(index);
+                        }
+                      });
+                    },
+                    title: Text(template.name),
+                    subtitle: Text(_templateSubtitle(template)),
+                  );
+                },
+              ),
+            ),
+            // Selected count indicator
+            if (_selected.isNotEmpty)
+              Padding(
+                padding: const EdgeInsets.symmetric(horizontal: 16),
+                child: Text(
+                  l10n.templatePickerSelected(_selected.length),
+                  style: theme.textTheme.bodySmall?.copyWith(
+                    color: theme.colorScheme.primary,
+                  ),
+                ),
+              ),
+            // Action buttons
+            Padding(
+              padding: const EdgeInsets.all(16),
+              child: Row(
+                children: [
+                  Expanded(
+                    child: OutlinedButton(
+                      onPressed: () => Navigator.of(context).pop(),
+                      child: Text(l10n.templatePickerSkip),
+                    ),
+                  ),
+                  const SizedBox(width: 12),
+                  Expanded(
+                    child: FilledButton(
+                      onPressed:
+                          _selected.isNotEmpty ? _onConfirmPressed : null,
+                      child: Text(l10n.templatePickerAdd),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ],
+        );
+      },
+    );
+  }
+}
+
+/// Shows the template picker bottom sheet and returns the selected templates.
+///
+/// Returns the list of selected [TaskTemplate]s, or null if user skipped.
+Future<List<TaskTemplate>?> showTemplatePickerSheet({
+  required BuildContext context,
+  required String roomType,
+  required List<TaskTemplate> templates,
+}) {
+  return showModalBottomSheet<List<TaskTemplate>>(
+    context: context,
+    isScrollControlled: true,
+    useSafeArea: true,
+    shape: const RoundedRectangleBorder(
+      borderRadius: BorderRadius.vertical(top: Radius.circular(16)),
+    ),
+    builder: (context) {
+      return TemplatePickerSheet(
+        roomType: roomType,
+        templates: templates,
+        onConfirm: (selected) {
+          Navigator.of(context).pop(selected);
+        },
+      );
+    },
+  );
+}

lib/l10n/app_de.arb

@@ -59,5 +59,14 @@
   "taskDeleteConfirmAction": "L\u00f6schen",
   "taskEmptyTitle": "Noch keine Aufgaben",
   "taskEmptyMessage": "Erstelle die erste Aufgabe f\u00fcr diesen Raum.",
-  "taskEmptyAction": "Aufgabe erstellen"
+  "taskEmptyAction": "Aufgabe erstellen",
+  "templatePickerTitle": "Aufgaben aus Vorlagen hinzuf\u00fcgen?",
+  "templatePickerSkip": "\u00dcberspringen",
+  "templatePickerAdd": "Hinzuf\u00fcgen",
+  "templatePickerSelected": "{count} ausgew\u00e4hlt",
+  "@templatePickerSelected": {
+    "placeholders": {
+      "count": { "type": "int" }
+    }
+  }
 }

lib/l10n/app_localizations.dart

@@ -393,6 +393,30 @@ abstract class AppLocalizations {
   /// In de, this message translates to:
   /// **'Aufgabe erstellen'**
   String get taskEmptyAction;
+
+  /// No description provided for @templatePickerTitle.
+  ///
+  /// In de, this message translates to:
+  /// **'Aufgaben aus Vorlagen hinzuf\u00fcgen?'**
+  String get templatePickerTitle;
+
+  /// No description provided for @templatePickerSkip.
+  ///
+  /// In de, this message translates to:
+  /// **'\u00dcberspringen'**
+  String get templatePickerSkip;
+
+  /// No description provided for @templatePickerAdd.
+  ///
+  /// In de, this message translates to:
+  /// **'Hinzuf\u00fcgen'**
+  String get templatePickerAdd;
+
+  /// No description provided for @templatePickerSelected.
+  ///
+  /// In de, this message translates to:
+  /// **'{count} ausgew\u00e4hlt'**
+  String templatePickerSelected(int count);
 }
 
 class _AppLocalizationsDelegate

lib/l10n/app_localizations_de.dart

@@ -164,4 +164,18 @@ class AppLocalizationsDe extends AppLocalizations {
 
   @override
   String get taskEmptyAction => 'Aufgabe erstellen';
+
+  @override
+  String get templatePickerTitle => 'Aufgaben aus Vorlagen hinzuf\u00fcgen?';
+
+  @override
+  String get templatePickerSkip => '\u00dcberspringen';
+
+  @override
+  String get templatePickerAdd => 'Hinzuf\u00fcgen';
+
+  @override
+  String templatePickerSelected(int count) {
+    return '$count ausgew\u00e4hlt';
+  }
 }