feat: Adds thermal balance point, still need to implement economic balance point.

Sources/ViewController/Live.swift

@@ -112,13 +112,16 @@ extension ViewController: DependencyKey {
       case let .heatingBalancePoint(route):
         switch route {
         case let .index(mode: mode, heatLossMode: heatLossMode):
-          return request.respond(HeatingBalancePointForm(mode: mode, heatLossMode: heatLossMode, response: nil))
+          return request.respond(HeatingBalancePointForm(
+            mode: mode,
+            heatLossMode: heatLossMode,
+            response: nil
+          ))
         case let .heatLossFields(mode: mode):
-          logger.debug("Heat loss mode: \(mode)")
           return HeatingBalancePointForm.HeatLossFields(mode: mode)
-        case .submit:
-          // FIX:
-          fatalError()
+        case let .submit(request):
+          let response = try await request.respond(logger: logger)
+          return HeatingBalancePointResponse(response: response)
         }
 
       case let .hvacSystemPerformance(route):