feat: add --ids-only flag to --list mode for scripting

Outputs one ID per line with no header. Errors if used with any mode
other than --list. Works with both local and client (remote) list.

src/modes/list.rs

@@ -5,7 +5,7 @@
 /// including table, JSON, and YAML.
 use crate::config;
 use crate::modes::common::ColumnType;
-use crate::modes::common::{OutputFormat, apply_color, apply_table_attribute, format_size};
+use crate::modes::common::{apply_color, apply_table_attribute, format_size, OutputFormat};
 use crate::services::item_service::ItemService;
 use crate::services::types::ItemWithMeta;
 use anyhow::{Context, Result};
@@ -104,6 +104,15 @@ pub fn mode_list(
         .collect();
     let items_with_meta = item_service.list_items(conn, tags, &meta_filter)?;
 
+    if settings.ids_only {
+        for item_with_meta in &items_with_meta {
+            if let Some(id) = item_with_meta.item.id {
+                println!("{id}");
+            }
+        }
+        return Ok(());
+    }
+
     let output_format = crate::modes::common::settings_output_format(settings);
 
     if output_format != OutputFormat::Table {