Unable to install localstack

**Describe the bug**
2025-09-16 15:23:45.152 [error] aws.toolkit.installLocalStack: Error: Failed to install LocalStack extension
-> NotFound: The extension 'localstack.localstack' cannot be installed because it was not found.

**To Reproduce**
Try to install localstack

**Expected behavior**
localstack extension found

**Screenshots**
n/a

**Toolkit Logs**
2025-09-16 15:20:42.681 [warning] telemetry: invalid Metric: "appBuilder_startWalkthrough" emitted without the `result` property, which is always required. Consider using `.run()` instead of `.emit()`, which will set these properties automatically. See https://github.com/aws/aws-toolkit-vscode/blob/master/docs/telemetry.md#guidelines
2025-09-16 15:20:46.900 [error] aws.toolkit.installLocalStack: Error: Failed to install LocalStack extension
-> NotFound: The extension 'localstack.localstack' cannot be installed because it was not found.
2025-09-16 15:23:39.433 [info] telemetry: sent batch (size=20)
2025-09-16 15:23:39.653 [info] telemetry: sent batch (size=14)
2025-09-16 15:23:45.152 [error] aws.toolkit.installLocalStack: Error: Failed to install LocalStack extension
-> NotFound: The extension 'localstack.localstack' cannot be installed because it was not found.
2025-09-16 15:23:47.084 [error] aws.toolkit.installLocalStack: Error: Failed to install LocalStack extension
-> NotFound: The extension 'localstack.localstack' cannot be installed because it was not found.
2025-09-16 15:25:54.857 [warning] telemetry: invalid Metric: "appBuilder_startWalkthrough" emitted without the `result` property, which is always required. Consider using `.run()` instead of `.emit()`, which will set these properties automatically. See https://github.com/aws/aws-toolkit-vscode/blob/master/docs/telemetry.md#guidelines

**Development System (please complete the following information):**
Version: 1.5.11 (user setup)
VSCode Version: 1.99.3
Commit: 2f2737de9aa376933d975ae30290447c910fdf40
Date: 2025-09-05T03:48:32.332Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.19045
- AWS Toolkit for Visual Studio Version: 3.74

**Additional context**

Start by reproducing the LocalStack installation through the AWS Toolkit using the reported VS Code and toolkit versions. Trace the installLocalStack flow and the extension identifier localstack.localstack, then verify that the extension can be found and installed without the reported NotFound error.

Written by the indexing model from the issue text.