feat(ui): 统一应用主题色为天空蓝并优化渐变背景

将应用主色调从 '#BBF246' 更改为 '#87CEEB'（天空蓝），并更新所有相关组件和页面中的颜色引用。同时为多个页面添加统一的渐变背景，提升视觉效果和用户体验。新增压力分析模态框组件，并优化压力计组件的交互与显示逻辑。更新应用图标和启动图资源。

components/BMICard.tsx

@@ -1,20 +1,21 @@
+import { Colors } from '@/constants/Colors';
 import { useAuthGuard } from '@/hooks/useAuthGuard';
 import {
-    BMI_CATEGORIES,
-    canCalculateBMI,
-    getBMIResult,
-    type BMIResult
+  BMI_CATEGORIES,
+  canCalculateBMI,
+  getBMIResult,
+  type BMIResult
 } from '@/utils/bmi';
 import { Ionicons } from '@expo/vector-icons';
 import React, { useState } from 'react';
 import {
-    Dimensions,
-    Modal,
-    Pressable,
-    StyleSheet,
-    Text,
-    TouchableOpacity,
-    View
+  Dimensions,
+  Modal,
+  Pressable,
+  StyleSheet,
+  Text,
+  TouchableOpacity,
+  View
 } from 'react-native';
 import Toast from 'react-native-toast-message';
 
@@ -62,7 +63,7 @@ export function BMICard({ weight, height, style, compact = false }: BMICardProps
     if (!canCalculate) {
       // 缺少数据的情况
       return (
-        <TouchableOpacity 
+        <TouchableOpacity
           style={[styles.incompleteContent, compact && styles.compactIncompleteContent]}
           onPress={handleShowInfoModal}
           activeOpacity={0.8}
@@ -118,8 +119,8 @@ export function BMICard({ weight, height, style, compact = false }: BMICardProps
 
     // 有完整数据的情况
     return (
-      <TouchableOpacity 
-        style={[styles.completeContent, { backgroundColor: bmiResult?.backgroundColor }, compact && styles.compactCompleteContent]}
+      <TouchableOpacity
+        style={styles.completeContent}
         onPress={handleShowInfoModal}
         activeOpacity={0.8}
       >
@@ -193,7 +194,7 @@ export function BMICard({ weight, height, style, compact = false }: BMICardProps
           style={styles.modalBackdrop}
           onPress={handleHideInfoModal}
         >
-          <Pressable 
+          <Pressable
             style={styles.modalContainer}
             onPress={(e) => e.stopPropagation()}
           >
@@ -234,7 +235,7 @@ export function BMICard({ weight, height, style, compact = false }: BMICardProps
                 <View style={styles.categoriesGrid}>
                   {BMI_CATEGORIES.map((category, index) => {
                     const colors = index === 0 ? { bg: '#FEF3C7', text: '#B45309' } :
-                      index === 1 ? { bg: '#E8F5E8', text: '#2D5016' } :
+                      index === 1 ? { bg: '#E8F5E8', text: Colors.light.accentGreenDark } :
                         index === 2 ? { bg: '#FEF3C7', text: '#B45309' } :
                           { bg: '#FEE2E2', text: '#B91C1C' };
 
@@ -289,6 +290,7 @@ const styles = StyleSheet.create({
     padding: 18,
     marginBottom: 16,
     overflow: 'hidden',
+    backgroundColor: '#FFFFFF',
   },
   cardHeader: {
     flexDirection: 'row',
@@ -320,7 +322,7 @@ const styles = StyleSheet.create({
 
   // 缺少数据时的样式
   incompleteContent: {
-    minHeight: 120,
+    minHeight: 80,
     backgroundColor: '#FFFFFF',
     borderRadius: 22,
     padding: 18,
@@ -345,7 +347,7 @@ const styles = StyleSheet.create({
     flexDirection: 'row',
     alignItems: 'center',
     justifyContent: 'center',
-    backgroundColor: '#F3F4F6',
+    backgroundColor: '#ffffff',
     borderRadius: 12,
     paddingVertical: 12,
     paddingHorizontal: 16,
@@ -359,7 +361,7 @@ const styles = StyleSheet.create({
 
   // 有完整数据时的样式
   completeContent: {
-    minHeight: 120,
+    minHeight: 80,
     borderRadius: 22,
     padding: 18,
     margin: -18,
@@ -398,12 +400,12 @@ const styles = StyleSheet.create({
 
   // 紧凑模式样式
   compactIncompleteContent: {
-    minHeight: 110,
+    minHeight: 80,
     padding: 14,
     margin: -14,
   },
   compactCompleteContent: {
-    minHeight: 110,
+    minHeight: 80,
     padding: 14,
     margin: -14,
   },
@@ -427,7 +429,7 @@ const styles = StyleSheet.create({
     flex: 1,
   },
   compactBMIValue: {
-    fontSize: 28,
+    fontSize: 24,
     fontWeight: '800',
     marginBottom: 4,
   },
@@ -491,13 +493,13 @@ const styles = StyleSheet.create({
     alignItems: 'center',
     justifyContent: 'center',
   },
-  
+
   // 内容区域样式
   modalContent: {
     paddingHorizontal: 20,
     paddingBottom: 24,
   },
-  
+
   // 介绍部分
   introSection: {
     marginBottom: 20,
@@ -522,7 +524,7 @@ const styles = StyleSheet.create({
     fontWeight: '600',
     textAlign: 'center',
   },
-  
+
   // 分类部分
   categoriesSection: {
     marginBottom: 18,
@@ -567,7 +569,7 @@ const styles = StyleSheet.create({
     fontWeight: '500',
     opacity: 0.9,
   },
-  
+
   // 健康提示
   healthTips: {
     backgroundColor: '#F9FAFB',
@@ -593,7 +595,7 @@ const styles = StyleSheet.create({
     color: '#374151',
     lineHeight: 18,
   },
-  
+
   // 免责声明紧凑版
   disclaimerCompact: {
     flexDirection: 'row',