feat: Moves api controller to it's own module.

Sources/DatabaseClientLive/Users+live.swift

@@ -25,7 +25,9 @@ public extension DatabaseClient.Users {
     } login: { login in
       try login.validate()
 
-      var query = UserModel.query(on: database)
+      var query = UserModel
+        .query(on: database)
+        .with(\.$token)
 
       if let username = login.username {
         query = query.filter(\UserModel.$username == username)
@@ -37,15 +39,19 @@ public extension DatabaseClient.Users {
         throw NotFoundError()
       }
 
-      let token = try user.generateToken()
+      let token: User.Token
 
-      try await token.save(on: database)
+      // Check if the user already has a token.
+      if let userToken = user.token {
+        token = try userToken.toDTO()
+      } else {
+        // Generate a new token for the user if they didn't have one.
+        let tokenModel = try user.generateToken()
+        try await tokenModel.save(on: database)
+        token = try tokenModel.toDTO()
+      }
 
-      return try User.Token(
-        id: token.requireID(),
-        userID: user.requireID(),
-        value: token.value
-      )
+      return token
 
     } logout: { id in
       guard let token = try await UserTokenModel.find(id, on: database)