fix(cli): allow prompts starting with hyphens in exec mode

Fixes bounty issue #1511

Clap treats arguments starting with '-' as flags by default.
Added 'allow_hyphen_values = true' to the prompt argument definition
to allow passing content like YAML frontmatter directly.

Author: factorydroid

cortex-cli/src/main.rs

@@ -208,7 +208,7 @@ enum Commands {
 #[derive(Args)]
 struct ExecCommand {
     /// Prompt to execute
-    #[arg(required = true)]
+    #[arg(required = true, allow_hyphen_values = true)]
     prompt: String,
 
     /// Output format (human, json, jsonl)