fix: enforce mandatory start/end dates and at least one identifier flag

Co-authored-by: aider (openai/qwen3-coder:30b-a3b-q4_K_M) <aider@aider.chat>

cmd/acb/main.go

@@ -24,8 +24,15 @@ func main() {
 	flag.Parse()
 
 	// Check required flags
-	if *jiraUser == "" || *proj == "" || *ghusername == "" || *start == "" || *end == "" || *employeename == "" {
+	if *start == "" || *end == "" {
-		fmt.Println("All flags are required")
+		fmt.Println("Error: start and end dates are required")
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	// Check that at least one of employee name, jira user, project, or ghusername is provided
+	if *employeename == "" && *jiraUser == "" && *proj == "" && *ghusername == "" {
+		fmt.Println("Error: at least one of employee name, jira user, project, or ghusername must be provided")
 		flag.Usage()
 		os.Exit(1)
 	}