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/tests/auth_tests.rs

@@ -6,22 +6,24 @@ const BASE_URL: &str = "http://127.0.0.1:8000";
 #[tokio::test]
 async fn test_health_check() {
     let client = Client::new();
-    let response = client.get(&format!("{}/health", BASE_URL))
+    let response = client
+        .get(&format!("{}/health", BASE_URL))
         .send()
         .await
         .expect("Failed to send request");
-    
+
     assert_eq!(response.status(), 200);
 }
 
 #[tokio::test]
 async fn test_ready_check() {
     let client = Client::new();
-    let response = client.get(&format!("{}/ready", BASE_URL))
+    let response = client
+        .get(&format!("{}/ready", BASE_URL))
         .send()
         .await
         .expect("Failed to send request");
-    
+
     assert_eq!(response.status(), 200);
 }
 
@@ -29,7 +31,7 @@ async fn test_ready_check() {
 async fn test_register_user() {
     let client = Client::new();
     let email = format!("test_{}@example.com", uuid::Uuid::new_v4());
-    
+
     let payload = json!({
         "email": email,
         "password_hash": "hashed_password_placeholder",
@@ -37,15 +39,16 @@ async fn test_register_user() {
         "recovery_phrase_iv": "iv_placeholder",
         "recovery_phrase_auth_tag": "auth_tag_placeholder"
     });
-    
-    let response = client.post(&format!("{}/api/auth/register", BASE_URL))
+
+    let response = client
+        .post(&format!("{}/api/auth/register", BASE_URL))
         .json(&payload)
         .send()
         .await
         .expect("Failed to send request");
-    
+
     assert_eq!(response.status(), 200);
-    
+
     let json: Value = response.json().await.expect("Failed to parse JSON");
     assert_eq!(json["email"], email);
     assert!(json["user_id"].is_string());
@@ -55,7 +58,7 @@ async fn test_register_user() {
 async fn test_login() {
     let client = Client::new();
     let email = format!("test_{}@example.com", uuid::Uuid::new_v4());
-    
+
     // First register a user
     let register_payload = json!({
         "email": email,
@@ -64,27 +67,29 @@ async fn test_login() {
         "recovery_phrase_iv": "iv_placeholder",
         "recovery_phrase_auth_tag": "auth_tag_placeholder"
     });
-    
-    let _reg_response = client.post(&format!("{}/api/auth/register", BASE_URL))
+
+    let _reg_response = client
+        .post(&format!("{}/api/auth/register", BASE_URL))
         .json(&register_payload)
         .send()
         .await
         .expect("Failed to send request");
-    
+
     // Now login
     let login_payload = json!({
         "email": email,
         "password_hash": "hashed_password_placeholder"
     });
-    
-    let response = client.post(&format!("{}/api/auth/login", BASE_URL))
+
+    let response = client
+        .post(&format!("{}/api/auth/login", BASE_URL))
         .json(&login_payload)
         .send()
         .await
         .expect("Failed to send request");
-    
+
     assert_eq!(response.status(), 200);
-    
+
     let json: Value = response.json().await.expect("Failed to parse JSON");
     assert!(json["access_token"].is_string());
     assert!(json["refresh_token"].is_string());
@@ -94,12 +99,13 @@ async fn test_login() {
 #[tokio::test]
 async fn test_get_profile_without_auth() {
     let client = Client::new();
-    
-    let response = client.get(&format!("{}/api/users/me", BASE_URL))
+
+    let response = client
+        .get(&format!("{}/api/users/me", BASE_URL))
         .send()
         .await
         .expect("Failed to send request");
-    
+
     // Should return 401 Unauthorized without auth token
     assert_eq!(response.status(), 401);
 }
@@ -108,7 +114,7 @@ async fn test_get_profile_without_auth() {
 async fn test_get_profile_with_auth() {
     let client = Client::new();
     let email = format!("test_{}@example.com", uuid::Uuid::new_v4());
-    
+
     // Register and login
     let register_payload = json!({
         "email": email,
@@ -117,36 +123,41 @@ async fn test_get_profile_with_auth() {
         "recovery_phrase_iv": "iv_placeholder",
         "recovery_phrase_auth_tag": "auth_tag_placeholder"
     });
-    
-    client.post(&format!("{}/api/auth/register", BASE_URL))
+
+    client
+        .post(&format!("{}/api/auth/register", BASE_URL))
         .json(&register_payload)
         .send()
         .await
         .expect("Failed to send request");
-    
+
     let login_payload = json!({
         "email": email,
         "password_hash": "hashed_password_placeholder"
     });
-    
-    let login_response = client.post(&format!("{}/api/auth/login", BASE_URL))
+
+    let login_response = client
+        .post(&format!("{}/api/auth/login", BASE_URL))
         .json(&login_payload)
         .send()
         .await
         .expect("Failed to send request");
-    
+
     let login_json: Value = login_response.json().await.expect("Failed to parse JSON");
-    let access_token = login_json["access_token"].as_str().expect("No access token");
-    
+    let access_token = login_json["access_token"]
+        .as_str()
+        .expect("No access token");
+
     // Get profile with auth token
-    let response = client.get(&format!("{}/api/users/me", BASE_URL))
+    let response = client
+        .get(&format!("{}/api/users/me", BASE_URL))
         .header("Authorization", format!("Bearer {}", access_token))
         .send()
         .await
         .expect("Failed to send request");
-    
+
     assert_eq!(response.status(), 200);
-    
+
     let json: Value = response.json().await.expect("Failed to parse JSON");
     assert_eq!(json["email"], email);
 }