대시보드 배너/타이틀 중앙정렬 + 타일 UI 편집(드래그 이동/크기조절) + 로그인 유지 기능 추가

- 이름/부제, "스마트 관리 시스템 메뉴" 제목을 중앙 정렬
- 타일을 1x1~4x4 크기로 자유 배치할 수 있는 편집 모드 추가 (6x4 캔버스, 삼성 One UI 위젯 편집 방식)
- 타일 배치는 계정별로 서버에 저장/복원 (dashboard_layout_controller.dart)
- 설정 화면(톱니바퀴 아이콘) > "UI 편집" 진입점 추가
- shared_preferences로 로그인 유지 기능 추가 (비밀번호는 저장하지 않음)

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

pubspec.lock

@@ -472,6 +472,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  path_provider_linux:
+    dependency: transitive
+    description:
+      name: path_provider_linux
+      sha256: "58c2005f147315b11e9b4a7bc889cd5203e250cba8e3f012dae259b4972b5c16"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.2"
+  path_provider_platform_interface:
+    dependency: transitive
+    description:
+      name: path_provider_platform_interface
+      sha256: "484838772624c3a4b94f1e44a3e19897fee738f2d5c4ce448443b0417f7c9dda"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.3"
+  path_provider_windows:
+    dependency: transitive
+    description:
+      name: path_provider_windows
+      sha256: bd6f00dbd873bfb70d0761682da2b3a2c2fccc2b9e84c495821639601d81afe7
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.0"
   permission_handler:
     dependency: "direct main"
     description:
@@ -544,6 +568,62 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.8"
+  shared_preferences:
+    dependency: "direct main"
+    description:
+      name: shared_preferences
+      sha256: c3025c5534b01739267eb7d76959bbc25a6d10f6988e1c2a3036940133dd10bf
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.5.5"
+  shared_preferences_android:
+    dependency: transitive
+    description:
+      name: shared_preferences_android
+      sha256: "1e12aafe408aa50da80edfd679a2a6bf63ba7ab37c7fa98286da459a757b3399"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.28"
+  shared_preferences_foundation:
+    dependency: transitive
+    description:
+      name: shared_preferences_foundation
+      sha256: "2ec3934efa51e46117f23031cc141b8fc878e8525b94ec1ea4f7f586cf1b47ea"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.5.7"
+  shared_preferences_linux:
+    dependency: transitive
+    description:
+      name: shared_preferences_linux
+      sha256: "580abfd40f415611503cae30adf626e6656dfb2f0cee8f465ece7b6defb40f2f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
+  shared_preferences_platform_interface:
+    dependency: transitive
+    description:
+      name: shared_preferences_platform_interface
+      sha256: "649dc798a33931919ea356c4305c2d1f81619ea6e92244070b520187b5140ef9"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.2"
+  shared_preferences_web:
+    dependency: transitive
+    description:
+      name: shared_preferences_web
+      sha256: c49bd060261c9a3f0ff445892695d6212ff603ef3115edbb448509d407600019
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.3"
+  shared_preferences_windows:
+    dependency: transitive
+    description:
+      name: shared_preferences_windows
+      sha256: "94ef0f72b2d71bc3e700e025db3710911bd51a71cefb65cc609dd0d9a982e3c1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -703,4 +783,4 @@ packages:
     version: "6.6.1"
 sdks:
   dart: ">=3.12.2 <4.0.0"
-  flutter: ">=3.41.0"
+  flutter: ">=3.44.0"