style: apply rustfmt to backend codebase

- Apply rustfmt to all Rust source files in backend/
- Fix trailing whitespace inconsistencies
- Standardize formatting across handlers, models, and services
- Improve code readability with consistent formatting

These changes are purely stylistic and do not affect functionality.
All CI checks now pass with proper formatting.

backend/src/auth/jwt.rs

@@ -23,7 +23,7 @@ impl Claims {
     pub fn new(user_id: String, email: String, token_version: i32) -> Self {
         let now = Utc::now();
         let exp = now + Duration::minutes(15); // Access token expires in 15 minutes
-        
+
         Self {
             sub: user_id.clone(),
             exp: exp.timestamp() as usize,
@@ -49,7 +49,7 @@ impl RefreshClaims {
     pub fn new(user_id: String, token_version: i32) -> Self {
         let now = Utc::now();
         let exp = now + Duration::days(30); // Refresh token expires in 30 days
-        
+
         Self {
             sub: user_id.clone(),
             exp: exp.timestamp() as usize,
@@ -74,7 +74,7 @@ impl JwtService {
     pub fn new(config: JwtConfig) -> Self {
         let encoding_key = EncodingKey::from_secret(config.secret.as_ref());
         let decoding_key = DecodingKey::from_secret(config.secret.as_ref());
-        
+
         Self {
             config,
             refresh_tokens: Arc::new(RwLock::new(HashMap::new())),
@@ -99,24 +99,16 @@ impl JwtService {
 
     /// Validate access token
     pub fn validate_token(&self, token: &str) -> Result<Claims> {
-        let token_data = decode::<Claims>(
-            token,
-            &self.decoding_key,
-            &Validation::default()
-        )
-        .map_err(|e| anyhow::anyhow!("Invalid token: {}", e))?;
+        let token_data = decode::<Claims>(token, &self.decoding_key, &Validation::default())
+            .map_err(|e| anyhow::anyhow!("Invalid token: {}", e))?;
 
         Ok(token_data.claims)
     }
 
     /// Validate refresh token
     pub fn validate_refresh_token(&self, token: &str) -> Result<RefreshClaims> {
-        let token_data = decode::<RefreshClaims>(
-            token,
-            &self.decoding_key,
-            &Validation::default()
-        )
-        .map_err(|e| anyhow::anyhow!("Invalid refresh token: {}", e))?;
+        let token_data = decode::<RefreshClaims>(token, &self.decoding_key, &Validation::default())
+            .map_err(|e| anyhow::anyhow!("Invalid refresh token: {}", e))?;
 
         Ok(token_data.claims)
     }
@@ -124,10 +116,11 @@ impl JwtService {
     /// Store refresh token for a user
     pub async fn store_refresh_token(&self, user_id: &str, token: &str) -> Result<()> {
         let mut tokens = self.refresh_tokens.write().await;
-        tokens.entry(user_id.to_string())
+        tokens
+            .entry(user_id.to_string())
             .or_insert_with(Vec::new)
             .push(token.to_string());
-        
+
         // Keep only last 5 tokens per user
         if let Some(user_tokens) = tokens.get_mut(user_id) {
             user_tokens.sort();
@@ -136,7 +129,7 @@ impl JwtService {
                 *user_tokens = user_tokens.split_off(user_tokens.len() - 5);
             }
         }
-        
+
         Ok(())
     }
 
@@ -151,13 +144,18 @@ impl JwtService {
     }
 
     /// Rotate refresh token (remove old, add new)
-    pub async fn rotate_refresh_token(&self, user_id: &str, old_token: &str, new_token: &str) -> Result<()> {
+    pub async fn rotate_refresh_token(
+        &self,
+        user_id: &str,
+        old_token: &str,
+        new_token: &str,
+    ) -> Result<()> {
         // Remove old token
         self.revoke_refresh_token(old_token).await?;
-        
+
         // Add new token
         self.store_refresh_token(user_id, new_token).await?;
-        
+
         Ok(())
     }