refactor: apply clippy auto-fixes (162 warnings resolved)

- Fix needless borrows and references
- Collapse nested if statements
- Replace manual strip_prefix with str::strip_prefix()
- Remove redundant closures in map/unwrap_or_else
- Use Iterator::next_back() instead of rev().next()
- Simplify map_or patterns
- Use std::io::Error::other() instead of new(ErrorKind::Other, ..)
- Use div_ceil() instead of manual ceiling division
- Consolidate format! string arguments
- Various other idiomatic Rust improvements

39 files changed, 220 insertions(+), 320 deletions(-)

src/infrastructure/repositories/pg/user_pg_repository.rs

@@ -32,7 +32,7 @@ impl UserPgRepository {
                 UserRepositoryError::NotFound("User not found".to_string())
             },
             sqlx::Error::Database(db_err) => {
-                if db_err.code().map_or(false, |code| code == "23505") {
+                if db_err.code().is_some_and(|code| code == "23505") {
                     // PostgreSQL uniqueness violation code
                     UserRepositoryError::AlreadyExists(
                         "User or email already exists".to_string()
@@ -268,7 +268,7 @@ impl UserRepository for UserPgRepository {
                     .bind(user_clone.username())
                     .bind(user_clone.email())
                     .bind(user_clone.password_hash())
-                    .bind(&user_clone.role().to_string())
+                    .bind(user_clone.role().to_string())
                     .bind(user_clone.storage_quota_bytes())
                     .bind(user_clone.storage_used_bytes())
                     .bind(user_clone.updated_at())