style: apply rustfmt, fix clippy warnings, and minor code cleanup

Reformat Rust code with rustfmt, suppress clippy::too_many_arguments
for Tauri IPC commands, derive Default for AppSettings, fix unused
variable pattern in TableDataView, and add unit tests for utils.

src-tauri/src/models/settings.rs

@@ -1,20 +1,11 @@
 use serde::{Deserialize, Serialize};
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct AppSettings {
     pub mcp: McpSettings,
     pub docker: DockerSettings,
 }
 
-impl Default for AppSettings {
-    fn default() -> Self {
-        Self {
-            mcp: McpSettings::default(),
-            docker: DockerSettings::default(),
-        }
-    }
-}
-
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct McpSettings {
     pub enabled: bool,