feat: encrypted-history prompt, incoming-call alerts, message edit, panic button (v1.7.0+11)

P1 key_restore_prompt: offer recovery-key restore right after login
P2 incoming calls: mount overlay in app.dart + detect MSC3401 call.member
   (Element X signalling) — calls were previously invisible
P3 message edit: editMessage/EditMessage + Edit dialog (reactions/delete
   were already wired)
P5 panic button: new feature/panic module — hold-to-send alert text +
   m.location to a configured room; alert sent before geolocation so a
   denied permission never blocks it

All verified end-to-end in headless Chromium against production build.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/features/panic/data/panic_repository.dart

@@ -0,0 +1,142 @@
+// Version: 1.0.0 | Created: 2026-07-04
+// Panic button repository — config in Matrix account data plus the trigger
+// action: send an alert text message and (when the browser grants it) an
+// m.location pin to the configured room.
+//
+// The alert message is sent FIRST so a denied/slow geolocation permission can
+// never block the emergency alert itself.
+//
+// NOTE web-only geolocation (dart:js_interop + package:web). When native
+// Android/iOS builds happen, gate this behind a conditional import.
+
+import 'dart:async';
+import 'dart:js_interop';
+
+import 'package:flutter/foundation.dart';
+import 'package:matrix/matrix.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:web/web.dart' as web;
+
+import '../../../core/network/matrix_client.dart';
+
+part 'panic_repository.g.dart';
+
+/// Account-data event type holding the panic configuration.
+const kPanicConfigType = 'au.m8chat.panic';
+
+/// Panic button configuration.
+class PanicConfig {
+  const PanicConfig({required this.roomId, required this.message});
+
+  final String roomId;
+  final String message;
+
+  static PanicConfig? fromAccountData(Client client) {
+    final content = client.accountData[kPanicConfigType]?.content;
+    final roomId = content?['room_id'];
+    if (roomId is! String || roomId.isEmpty) return null;
+    final message = content?['message'];
+    return PanicConfig(
+      roomId: roomId,
+      message: message is String && message.isNotEmpty
+          ? message
+          : 'EMERGENCY: I need help. This is an automated alert from M8Chat.',
+    );
+  }
+}
+
+class PanicRepository {
+  PanicRepository({required Client client}) : _client = client;
+
+  final Client _client;
+
+  PanicConfig? get config => PanicConfig.fromAccountData(_client);
+
+  Future<void> saveConfig({
+    required String roomId,
+    required String message,
+  }) async {
+    final userId = _client.userID;
+    if (userId == null) throw Exception('Not logged in');
+    await _client.setAccountData(userId, kPanicConfigType, {
+      'room_id': roomId,
+      'message': message,
+    });
+  }
+
+  Future<void> clearConfig() async {
+    final userId = _client.userID;
+    if (userId == null) return;
+    await _client.setAccountData(userId, kPanicConfigType, {});
+  }
+
+  /// Fires the panic alert. Returns an error string, or null on success.
+  Future<String?> trigger() async {
+    final cfg = config;
+    if (cfg == null) return 'Panic button is not configured.';
+    final room = _client.getRoomById(cfg.roomId);
+    if (room == null) return 'Configured room is no longer available.';
+
+    // 1. The alert text goes out first — never blocked by geolocation.
+    try {
+      await room.sendTextEvent('\u{1F6A8} ${cfg.message}');
+    } on Exception catch (e) {
+      return 'Could not send alert: $e';
+    }
+
+    // 2. Best-effort location pin.
+    final position = await _currentPosition();
+    if (position != null) {
+      final (lat, lon) = position;
+      final geoUri = 'geo:$lat,$lon';
+      try {
+        await room.sendEvent({
+          'msgtype': 'm.location',
+          'body': 'Emergency location: $geoUri',
+          'geo_uri': geoUri,
+          'org.matrix.msc3488.location': {'uri': geoUri},
+          'org.matrix.msc3488.asset': {'type': 'm.pin'},
+        }, type: 'm.room.message');
+      } on Exception catch (e) {
+        debugPrint('[Panic] location send failed: $e');
+      }
+    } else {
+      debugPrint('[Panic] no geolocation available — alert sent without it');
+    }
+    return null;
+  }
+
+  /// Browser geolocation with a hard 10s budget. Null when denied/unavailable.
+  Future<(double, double)?> _currentPosition() async {
+    final completer = Completer<(double, double)?>();
+    try {
+      web.window.navigator.geolocation.getCurrentPosition(
+        (web.GeolocationPosition pos) {
+          if (!completer.isCompleted) {
+            completer.complete((pos.coords.latitude, pos.coords.longitude));
+          }
+        }.toJS,
+        (web.GeolocationPositionError err) {
+          if (!completer.isCompleted) completer.complete(null);
+        }.toJS,
+        web.PositionOptions(
+          enableHighAccuracy: true,
+          timeout: 8000,
+          maximumAge: 60000,
+        ),
+      );
+    } catch (e) {
+      debugPrint('[Panic] geolocation API unavailable: $e');
+      return null;
+    }
+    return completer.future.timeout(
+      const Duration(seconds: 10),
+      onTimeout: () => null,
+    );
+  }
+}
+
+@Riverpod(keepAlive: true)
+PanicRepository panicRepository(Ref ref) {
+  return PanicRepository(client: ref.watch(matrixClientProvider));
+}