feat(ui): add ShareSheet component for multi-channel post sharing

Add ShareSheet component that provides native sharing options (WeChat, Moments, copy link, etc.) replacing the previous clipboard-only approach. Also change like icon from heart to thumb-up to better match the share functionality.

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "carrot_bbs",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "carrot_bbs",
-      "version": "1.0.2",
+      "version": "1.0.3",
       "dependencies": {
         "@expo/vector-icons": "^15.1.1",
         "@react-native-async-storage/async-storage": "^2.2.0",
@@ -19,7 +19,6 @@
         "axios": "^1.13.6",
         "date-fns": "^4.1.0",
         "expo": "~55.0.4",
-        "expo-background-fetch": "~55.0.10",
         "expo-background-task": "~55.0.10",
         "expo-camera": "^55.0.10",
         "expo-constants": "~55.0.7",
@@ -52,6 +51,7 @@
         "react-native-reanimated": "^4.2.1",
         "react-native-safe-area-context": "~5.6.2",
         "react-native-screens": "~4.23.0",
+        "react-native-share": "^12.2.6",
         "react-native-sse": "^1.2.1",
         "react-native-web": "^0.21.0",
         "react-native-webrtc": "^124.0.7",
@@ -5549,18 +5549,6 @@
         "react-native": "*"
       }
     },
-    "node_modules/expo-background-fetch": {
-      "version": "55.0.10",
-      "resolved": "https://registry.npmmirror.com/expo-background-fetch/-/expo-background-fetch-55.0.10.tgz",
-      "integrity": "sha512-JRSlQ2GEigUxKqHi11xLPz5/T02O7YzsV1xNKDOxr2SXSERmAN9WFD9l2F9SDw5tUz53ewI1kndHQ6FmSu+7Tw==",
-      "license": "MIT",
-      "dependencies": {
-        "expo-task-manager": "~55.0.10"
-      },
-      "peerDependencies": {
-        "expo": "*"
-      }
-    },
     "node_modules/expo-background-task": {
       "version": "55.0.10",
       "resolved": "https://registry.npmmirror.com/expo-background-task/-/expo-background-task-55.0.10.tgz",
@@ -9748,6 +9736,15 @@
         "react-native": "*"
       }
     },
+    "node_modules/react-native-share": {
+      "version": "12.2.6",
+      "resolved": "https://registry.npmmirror.com/react-native-share/-/react-native-share-12.2.6.tgz",
+      "integrity": "sha512-K9jZCQaTIqSNG37kMVygU1rflVMJm2g0ikslnbbmQ7EgsckYpw7ipePyp01E64hG+HrWNl+z9ZnFWLCC6H+Tiw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=16"
+      }
+    },
     "node_modules/react-native-sse": {
       "version": "1.2.1",
       "resolved": "https://registry.npmmirror.com/react-native-sse/-/react-native-sse-1.2.1.tgz",