feat: 健康仪表盘配色调整 + 登录页品牌升级 + iOS 配置 + 隐私文案修订 + 文档清理

## UI 配色
- 健康仪表盘: 背景从蓝紫粉三色渐变改为 #4FACFE 纯色蓝, 白字清晰不抢眼
- app_colors / app_design_tokens / app_theme: 配色体系微调
- 多个 widget 和页面跟随配色更新(health_drawer/admin_drawer/doctor_drawer/enterprise_widgets 等)

## 登录页品牌升级
- 新增品牌素材: drawer_background_v2 / login_background_v2 / health_login_character_transparent
- login_page 重构, 接入新品牌视觉
- app.dart 启动流程调整

## iOS / Android 配置
- Info.plist: 权限描述调整
- AppIcon / LaunchImage: 资源更新
- AndroidManifest: 权限微调

## 隐私文案修订
- privacy.html: 蓝牙设备描述调整为"标准蓝牙血压服务", 移除未上线设备类型表述
- terms.html: 移除"在线医生咨询"相关条款, 服务范围收窄

## 通知中心
- notification_center_page: 重构通知项布局

## 其他
- 删除已完成的计划/spec 文档(ui-system-first-pass / apple-sign-in / secondary-page-color-refresh / notification-preferences-design / ui-design-system)
- 新增 native_navigation_test
- 新增 HANDOFF 交接文档
- home_message_order_test 更新
- .gitignore 调整

health_app/lib/pages/home/home_page.dart

@@ -1,6 +1,5 @@
 import 'dart:io';
 import 'dart:async';
-import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:image_picker/image_picker.dart';
@@ -31,6 +30,26 @@ class _HomePageState extends ConsumerState<HomePage>
   final _scaffoldKey = GlobalKey<ScaffoldState>();
   String? _pickedImagePath;
   Timer? _notificationTimer;
+  double _conversationDragDistance = 0;
+
+  void _startConversationDrawerDrag(DragStartDetails details) {
+    _conversationDragDistance = 0;
+  }
+
+  void _updateConversationDrawerDrag(DragUpdateDetails details) {
+    _conversationDragDistance += details.delta.dx;
+    if (_conversationDragDistance < 0) {
+      _conversationDragDistance = 0;
+    }
+    if (_conversationDragDistance >= 42) {
+      _conversationDragDistance = 0;
+      _scaffoldKey.currentState?.openDrawer();
+    }
+  }
+
+  void _endConversationDrawerDrag(DragEndDetails details) {
+    _conversationDragDistance = 0;
+  }
 
   @override
   void initState() {
@@ -134,9 +153,7 @@ class _HomePageState extends ConsumerState<HomePage>
       key: _scaffoldKey,
       backgroundColor: const Color(0xFFFFFCFF),
       drawer: const HealthDrawer(),
-      drawerEnableOpenDragGesture: true,
-      drawerDragStartBehavior: DragStartBehavior.down,
-      drawerEdgeDragWidth: MediaQuery.sizeOf(context).width * 0.8,
+      drawerEnableOpenDragGesture: false,
       body: DecoratedBox(
         decoration: const BoxDecoration(
           gradient: LinearGradient(
@@ -150,8 +167,15 @@ class _HomePageState extends ConsumerState<HomePage>
             children: [
               _buildHeader(user),
               Expanded(
-                child: RepaintBoundary(
-                  child: _HomeMessages(scrollCtrl: _scrollCtrl),
+                child: GestureDetector(
+                  behavior: HitTestBehavior.opaque,
+                  onHorizontalDragStart: _startConversationDrawerDrag,
+                  onHorizontalDragUpdate: _updateConversationDrawerDrag,
+                  onHorizontalDragEnd: _endConversationDrawerDrag,
+                  onHorizontalDragCancel: () => _conversationDragDistance = 0,
+                  child: RepaintBoundary(
+                    child: _HomeMessages(scrollCtrl: _scrollCtrl),
+                  ),
                 ),
               ),
               _buildBottomBar(context),
@@ -197,7 +221,7 @@ class _HomePageState extends ConsumerState<HomePage>
                   '${_getGreeting()}，$name',
                   style: const TextStyle(
                     fontSize: 18,
-                    fontWeight: FontWeight.w800,
+                    fontWeight: FontWeight.w600,
                     color: AppColors.textPrimary,
                   ),
                 ),
@@ -657,7 +681,7 @@ class _HeaderIconButton extends StatelessWidget {
                   style: const TextStyle(
                     color: Colors.white,
                     fontSize: 10,
-                    fontWeight: FontWeight.w800,
+                    fontWeight: FontWeight.w600,
                   ),
                 ),
               ),