fix: address clippy warnings for to_string and map usage

- Implemented Display trait for EnvTag and RiskTag instead of inherent to_string
- Changed and_then to map in TagConfigWidget::with_config for better idiomatic Rust
- Removed unused enumerate index in passkey_confirm.rs
- Changed format! to .to_string() for static strings

Note: This only addresses the specific warnings that were causing
CI failure. Other pre-existing clippy warnings remain.

Co-Authored-By: Claude (glm-4.7) <noreply@anthropic.com>

Author: alphaqiu

src/tui/screens/passkey_confirm.rs

@@ -119,7 +119,7 @@ impl PasskeyConfirmScreen {
             Style::default().fg(Color::Gray),
         )));
         let mut first_line = Vec::new();
-        for (_i, word) in self.passkey_words.iter().take(display_count).enumerate() {
+        for word in self.passkey_words.iter().take(display_count) {
             first_line.push(Span::styled(
                 format!("{} ", word),
                 Style::default().fg(Color::Green).add_modifier(Modifier::BOLD),
@@ -131,7 +131,7 @@ impl PasskeyConfirmScreen {
 
         // Last 4 words
         summary_lines.push(Line::from(Span::styled(
-            format!("后 4 词:"),
+            "后 4 词:".to_string(),
             Style::default().fg(Color::Gray),
         )));
         let mut last_line = Vec::new();

src/tui/tags/config.rs

@@ -1,4 +1,5 @@
 use serde::{Deserialize, Serialize};
+use std::fmt;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct TagConfig {
@@ -31,17 +32,18 @@ pub enum TagError {
     InvalidFormat { tag: String, expected: String },
 }
 
-impl EnvTag {
-    pub fn to_string(&self) -> String {
+impl fmt::Display for EnvTag {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Dev => "env:dev",
-            Self::Test => "env:test",
-            Self::Staging => "env:staging",
-            Self::Prod => "env:prod",
+            Self::Dev => write!(f, "env:dev"),
+            Self::Test => write!(f, "env:test"),
+            Self::Staging => write!(f, "env:staging"),
+            Self::Prod => write!(f, "env:prod"),
         }
-        .to_string()
     }
+}
 
+impl EnvTag {
     pub fn display_name(&self) -> &'static str {
         match self {
             Self::Dev => "dev (开发环境)",
@@ -61,16 +63,17 @@ impl EnvTag {
     }
 }
 
-impl RiskTag {
-    pub fn to_string(&self) -> String {
+impl fmt::Display for RiskTag {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Low => "risk:low",
-            Self::Medium => "risk:medium",
-            Self::High => "risk:high",
+            Self::Low => write!(f, "risk:low"),
+            Self::Medium => write!(f, "risk:medium"),
+            Self::High => write!(f, "risk:high"),
         }
-        .to_string()
     }
+}
 
+impl RiskTag {
     pub fn display_name(&self) -> &'static str {
         match self {
             Self::Low => "low (低风险)",

src/tui/tags/widget.rs

@@ -70,17 +70,17 @@ impl TagConfigWidget {
     /// * `credential_name` - Name of the credential being configured
     /// * `config` - Existing tag configuration to load
     pub fn with_config(credential_name: String, config: TagConfig) -> Self {
-        let selected_env = config.env.and_then(|env| match env {
-            EnvTag::Dev => Some(0),
-            EnvTag::Test => Some(1),
-            EnvTag::Staging => Some(2),
-            EnvTag::Prod => Some(3),
+        let selected_env = config.env.map(|env| match env {
+            EnvTag::Dev => 0,
+            EnvTag::Test => 1,
+            EnvTag::Staging => 2,
+            EnvTag::Prod => 3,
         });
 
-        let selected_risk = config.risk.and_then(|risk| match risk {
-            RiskTag::Low => Some(0),
-            RiskTag::Medium => Some(1),
-            RiskTag::High => Some(2),
+        let selected_risk = config.risk.map(|risk| match risk {
+            RiskTag::Low => 0,
+            RiskTag::Medium => 1,
+            RiskTag::High => 2,
         });
 
         Self {