fix: resolve relative manifest paths, base64 demo icon

app/src/main/java/top/yeij/hearth/webapp/WebAppRepository.kt

@@ -1,5 +1,6 @@
 package top.yeij.hearth.webapp
 
+import android.util.Base64
 import android.util.Log
 import com.google.gson.Gson
 import top.yeij.hearth.cache.CacheManager
@@ -69,14 +70,16 @@ class WebAppRepository(
     // 内置示例 webapp（打包在 assets 内，无需服务器）
     // Builtin demo webapp (bundled in assets, no server required)
     private fun builtinWebApps(): List<WebApp> {
+        val svg = "<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'>" +
+            "<rect width='24' height='24' rx='6' fill='#ff6900'/>" +
+            "<text x='12' y='17' font-size='13' text-anchor='middle' fill='white'>H</text></svg>"
+        val icon = "data:image/svg+xml;base64," +
+            Base64.encodeToString(svg.toByteArray(Charsets.UTF_8), Base64.NO_WRAP)
         return listOf(
             WebApp(
                 id = "demo",
                 name = "示例应用",
-                icon = "data:image/svg+xml;utf8," +
-                    "<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'>" +
-                    "<rect width='24' height='24' rx='6' fill='%23ff6900'/>" +
-                    "<text x='12' y='17' font-size='13' text-anchor='middle' fill='white'>H</text></svg>",
+                icon = icon,
                 url = "file:///android_asset/webapps/demo/index.html",
             )
         )
@@ -103,7 +106,13 @@ class WebAppRepository(
             val offlineMap = map["offline"] as? Map<*, *>
             val offline = offlineMap?.get("package") as? String
             val offlineVersion = offlineMap?.get("version") as? String
-            WebApp(id, name, icon, url, offline, offlineVersion)
+            WebApp(
+                id, name,
+                resolvePath(icon),
+                resolvePath(url),
+                offline?.let { resolvePath(it) },
+                offlineVersion,
+            )
         }
     }
 
@@ -111,4 +120,16 @@ class WebAppRepository(
         private const val TAG = "HearthWebApp"
         private const val KEY = "webapp-manifest"
     }
+
+    // 相对路径拼服务器根；绝对 URL / data URI / file URI 直接返回
+    // Resolve a relative path against the server root; return absolute URL / data
+    // URI / file URI as-is
+    private fun resolvePath(path: String): String {
+        if (path.startsWith("http://") || path.startsWith("https://") ||
+            path.startsWith("data:") || path.startsWith("file:")
+        ) {
+            return path
+        }
+        return serverUrl.trimEnd('/') + "/" + path.trimStart('/')
+    }
 }