Fix 2025.3 platform dependency resolution

- Revert sdkVersion to '2025.3' (let Gradle map to correct build)
- Change IdeFlavor from IC to IU for community builds (IC discontinued in 2025.3)
- Follows JetBrains recommendation to use standard IDE versions instead of build numbers

Author: aseemxs

buildSrc/src/main/kotlin/software/aws/toolkits/gradle/intellij/IdeVersions.kt

@@ -156,11 +156,11 @@ object IdeVersions {
         Profile(
             name = "2025.3",
             gateway = ProductProfile(
-                sdkVersion = "253.25908.29",
+                sdkVersion = "2025.3",
                 bundledPlugins = listOf("org.jetbrains.plugins.terminal")
             ),
             community = ProductProfile(
-                sdkVersion = "253.25908.29",
+                sdkVersion = "2025.3",
                 bundledPlugins = commonPlugins + listOf(
                     "com.intellij.java",
                     "com.intellij.gradle",
@@ -176,7 +176,7 @@ object IdeVersions {
                 )
             ),
             ultimate = ProductProfile(
-                sdkVersion = "253.25908.29",
+                sdkVersion = "2025.3",
                 bundledPlugins = commonPlugins + listOf(
                     "JavaScript",
                     "JavaScriptDebugger",

plugins/core/jetbrains-community/build.gradle.kts

@@ -45,7 +45,8 @@ tasks.compileKotlin {
 }
 
 intellijToolkit {
-    ideFlavor.set(IdeFlavor.IC)
+    // For 2025.3+, use IU (Ultimate) as the unified platform since IC (Community) was discontinued
+    ideFlavor.set(IdeFlavor.IU)
 }
 
 // expose intellij test framework to fixture consumers