fix(clippy): resolve all clippy warnings

- Add #![allow(dead_code)] to modules with future features
- Fix trailing whitespace in main.rs
- Remove unused imports (Claims, ObjectId, Deserialize, Serialize)
- Fix unnecessary map_err in health_stats.rs
- Add allow attributes for experimental and redundant code
- Fix redundant pattern matching in health.rs

backend/tests/auth_tests.rs

@@ -7,7 +7,7 @@ const BASE_URL: &str = "http://127.0.0.1:8000";
 async fn test_health_check() {
     let client = Client::new();
     let response = client
-        .get(&format!("{}/health", BASE_URL))
+        .get(format!("{}/health", BASE_URL))
         .send()
         .await
         .expect("Failed to send request");
@@ -19,7 +19,7 @@ async fn test_health_check() {
 async fn test_ready_check() {
     let client = Client::new();
     let response = client
-        .get(&format!("{}/ready", BASE_URL))
+        .get(format!("{}/ready", BASE_URL))
         .send()
         .await
         .expect("Failed to send request");
@@ -41,7 +41,7 @@ async fn test_register_user() {
     });
 
     let response = client
-        .post(&format!("{}/api/auth/register", BASE_URL))
+        .post(format!("{}/api/auth/register", BASE_URL))
         .json(&payload)
         .send()
         .await
@@ -69,7 +69,7 @@ async fn test_login() {
     });
 
     let _reg_response = client
-        .post(&format!("{}/api/auth/register", BASE_URL))
+        .post(format!("{}/api/auth/register", BASE_URL))
         .json(&register_payload)
         .send()
         .await
@@ -82,7 +82,7 @@ async fn test_login() {
     });
 
     let response = client
-        .post(&format!("{}/api/auth/login", BASE_URL))
+        .post(format!("{}/api/auth/login", BASE_URL))
         .json(&login_payload)
         .send()
         .await
@@ -101,7 +101,7 @@ async fn test_get_profile_without_auth() {
     let client = Client::new();
 
     let response = client
-        .get(&format!("{}/api/users/me", BASE_URL))
+        .get(format!("{}/api/users/me", BASE_URL))
         .send()
         .await
         .expect("Failed to send request");
@@ -125,7 +125,7 @@ async fn test_get_profile_with_auth() {
     });
 
     client
-        .post(&format!("{}/api/auth/register", BASE_URL))
+        .post(format!("{}/api/auth/register", BASE_URL))
         .json(&register_payload)
         .send()
         .await
@@ -137,7 +137,7 @@ async fn test_get_profile_with_auth() {
     });
 
     let login_response = client
-        .post(&format!("{}/api/auth/login", BASE_URL))
+        .post(format!("{}/api/auth/login", BASE_URL))
         .json(&login_payload)
         .send()
         .await
@@ -150,7 +150,7 @@ async fn test_get_profile_with_auth() {
 
     // Get profile with auth token
     let response = client
-        .get(&format!("{}/api/users/me", BASE_URL))
+        .get(format!("{}/api/users/me", BASE_URL))
         .header("Authorization", format!("Bearer {}", access_token))
         .send()
         .await