fix(knowledge): format code snippet output with newline

fix(container): add file validation check for Dockerfile

- Fix code snippet formatting in `KnowledgeFunctionProvider` to include a newline after the colon.
- Add file validation check in `RunDockerfileService` to ensure the file is valid before checking its language

Author: phodal

core/src/main/kotlin/cc/unitmesh/devti/bridge/knowledge/KnowledgeFunctionProvider.kt

@@ -95,7 +95,7 @@ class KnowledgeFunctionProvider : ToolchainFunctionProvider {
         }
 
         val lang = psiElements.firstOrNull()?.language?.displayName ?: ""
-        return "Here is $prop related code: ```$lang\n$elementText\n```"
+        return "Here is $prop related code:\n```$lang\n$elementText\n```"
     }
 
     fun commentSymbol(element: PsiElement): String {

exts/ext-container/src/233/main/kotlin/cc/unitmesh/container/RunDockerfileService.kt

@@ -18,7 +18,7 @@ import kotlinx.coroutines.runBlocking
 
 class RunDockerfileService : RunService {
     override fun isApplicable(project: Project, file: VirtualFile): Boolean = file.name == "Dockerfile" ||
-            runReadAction { PsiManager.getInstance(project).findFile(file)?.language == DockerLanguage.INSTANCE }
+            file.isValid && runReadAction { PsiManager.getInstance(project).findFile(file)?.language == DockerLanguage.INSTANCE }
 
     override fun runConfigurationClass(project: Project): Class<out RunProfile>? = null