[feat] add JSON and quiet output modes for models subcommands, update UI suppression logic, and enhance CLI test coverage

crates/polyscribe-cli/src/output.rs

@@ -0,0 +1,36 @@
+use std::io::{self, Write};
+
+#[derive(Clone, Debug)]
+pub enum OutputMode {
+    Json,
+    Human { quiet: bool },
+}
+
+impl OutputMode {
+    pub fn is_quiet(&self) -> bool {
+        matches!(self, OutputMode::Json) || matches!(self, OutputMode::Human { quiet: true })
+    }
+
+    pub fn print_json<T: serde::Serialize>(&self, v: &T) {
+        if let OutputMode::Json = self {
+            // Write compact JSON to stdout without prefixes
+            // and ensure a trailing newline for CLI ergonomics
+            let s = serde_json::to_string(v).unwrap_or_else(|e| format!("\"JSON_ERROR:{}\"", e));
+            println!("{}", s);
+        }
+    }
+
+    pub fn print_line(&self, s: impl AsRef<str>) {
+        match self {
+            OutputMode::Json => {
+                // Suppress human lines in JSON mode
+            }
+            OutputMode::Human { quiet } => {
+                if !quiet {
+                    let _ = writeln!(io::stdout(), "{}", s.as_ref());
+                }
+            }
+        }
+    }
+}
+