Add build args to Final Build Command Preview in UI

The "Final Build Command (Preview)" field now shows build arguments
that will be injected during deployment, matching the actual command
that runs. This provides transparency and helps users debug build issues.

Changes:
- Modified getDockerComposeBuildCommandPreviewProperty() to inject build args
- Uses same helper functions as deployment (generateDockerBuildArgs, injectDockerComposeBuildArgs)
- Respects use_build_secrets setting (build args only shown when disabled)
- Filters environment variables where is_buildtime = true

Example output:
docker compose -f ./docker-compose.yaml --env-file /artifacts/build-time.env build --build-arg FOO --build-arg BAR backend

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Livewire/Project/Application/General.php

@@ -1018,11 +1018,27 @@ public function getDockerComposeBuildCommandPreviewProperty(): string
         // Use relative path for clarity in preview (e.g., ./backend/docker-compose.yaml)
         // Actual deployment uses absolute path: /artifacts/{deployment_uuid}{base_directory}{docker_compose_location}
         // Build-time env path references ApplicationDeploymentJob::BUILD_TIME_ENV_PATH as source of truth
-        return injectDockerComposeFlags(
+        $command = injectDockerComposeFlags(
             $this->dockerComposeCustomBuildCommand,
             ".{$normalizedBase}{$this->dockerComposeLocation}",
             \App\Jobs\ApplicationDeploymentJob::BUILD_TIME_ENV_PATH
         );
+
+        // Inject build args if not using build secrets
+        if (! $this->application->settings->use_build_secrets) {
+            $buildTimeEnvs = $this->application->environment_variables()
+                ->where('is_buildtime', true)
+                ->get();
+
+            if ($buildTimeEnvs->isNotEmpty()) {
+                $buildArgs = generateDockerBuildArgs($buildTimeEnvs);
+                $buildArgsString = $buildArgs->implode(' ');
+
+                $command = injectDockerComposeBuildArgs($command, $buildArgsString);
+            }
+        }
+
+        return $command;
     }
 
     public function getDockerComposeStartCommandPreviewProperty(): string