feat: add shake detection functionality (#36)

* feat: add shake detection functionality and integrate vibration support

* feat: add shake detector settings page

lib/features/shake_detection/core/shake_detector.dart

@@ -0,0 +1,79 @@
+import 'dart:async';
+import 'dart:math';
+
+import 'package:logging/logging.dart';
+import 'package:sensors_plus/sensors_plus.dart';
+import 'package:vaani/settings/models/app_settings.dart';
+
+final _logger = Logger('ShakeDetector');
+
+class ShakeDetector {
+  final ShakeDetectionSettings _settings;
+  final Function()? onShakeDetected;
+
+  ShakeDetector(
+    this._settings,
+    this.onShakeDetected, {
+    startImmediately = true,
+  }) {
+    _logger.fine('ShakeDetector created with settings: $_settings');
+    if (startImmediately) {
+      start();
+    }
+  }
+
+  StreamSubscription? _accelerometerSubscription;
+
+  int _currentShakeCount = 0;
+
+  DateTime _lastShakeTime = DateTime.now();
+
+  void start() {
+    if (_accelerometerSubscription != null) {
+      _logger.warning('ShakeDetector is already running');
+      return;
+    }
+    _accelerometerSubscription =
+        userAccelerometerEventStream(samplingPeriod: _settings.samplingPeriod)
+            .listen((event) {
+      if (event.rms > _settings.threshold) {
+        _currentShakeCount++;
+
+        if (_currentShakeCount >= _settings.shakeTriggerCount &&
+            !isCoolDownNeeded()) {
+          _logger.fine('Shake detected $_currentShakeCount times');
+
+          onShakeDetected?.call();
+
+          _lastShakeTime = DateTime.now();
+          _currentShakeCount = 0;
+        }
+      } else {
+        _currentShakeCount = 0;
+      }
+    });
+
+    _logger.fine('ShakeDetector started');
+  }
+
+  void stop() {
+    _currentShakeCount = 0;
+    _accelerometerSubscription?.cancel();
+    _accelerometerSubscription = null;
+    _logger.fine('ShakeDetector stopped');
+  }
+
+  void dispose() {
+    stop();
+  }
+
+  bool isCoolDownNeeded() {
+    return _lastShakeTime
+        .add(_settings.shakeTriggerCoolDown)
+        .isAfter(DateTime.now());
+  }
+}
+
+extension UserAccelerometerEventRMS on UserAccelerometerEvent {
+  double get rms => sqrt(x * x + y * y + z * z);
+}