fix(devti): enhance shell command execution and clean up code

- Remove unnecessary comment in ProjectRule
- Improve shell command execution in ProcessExecutor by detecting available shells
- Use first available shell or default to 'bash' if no shells are detected

Author: phodal

core/src/main/kotlin/cc/unitmesh/devti/sketch/rule/ProjectRule.kt

@@ -25,7 +25,6 @@ class ProjectRule(private val project: Project) {
             return "<user-rule>\n$content\n</user-rule>"
         }
 
-        /// try .devin file
         val devinFile = project.lookupFile("$RULE_PATH/$filename.devin")
         if (devinFile != null) {
             val content = devinFile.readText()

core/src/main/kotlin/cc/unitmesh/devti/sketch/run/ProcessExecutor.kt

@@ -143,7 +143,8 @@ class ProcessExecutor(val project: Project) {
             AutoDevNotifications.notify(project, "Failed to get JAVA_HOME: ${e.message}")
         }
 
-        val commands: List<String> = listOf("bash", "--noprofile", "--norc", "-c", formatCommand(shellScript))
+        val shell = ShellUtil.detectShells().firstOrNull() ?: "bash"
+        val commands: List<String> = listOf(shell, "--noprofile", "--norc", "-c", formatCommand(shellScript))
 
         if (basedir != null) {
             commandLine.withWorkDirectory(basedir)