Silent failure when default port (3000) is already in use — no error notification or Output channel entry

Environment

• Extension: Live Preview v0.4.18
• VS Code: Remote - SSH (remote host: Linux/Ubuntu 24.04)
• Extension host: Remote (extension runs server-side)

Steps to Reproduce

1. Have port 3000 already occupied by another process on the remote host.
2. Open an HTML file in VS Code.
3. Run Show Preview (Internal Browser) from the Command Palette or editor context menu.

Expected Behavior

• An error notification is shown (e.g. "Live Preview: port 3000 is already in use. Change livePreview.portNumber in settings.")
• OR the Live Preview Output channel logs a clear error message
• OR the extension automatically retries on the next available port

Actual Behavior

• The command silently does nothing.
• No notification appears.
• The Live Preview channel does not appear in the Output panel dropdown at all — there is no indication the extension even attempted to start.
• Right-click → Show Preview from the editor context menu also silently fails with no feedback.

Workaround

Set livePreview.portNumber to a free port in workspace settings:

"livePreview.portNumber": 3900

After this change, Show Preview works immediately.

Impact

The failure mode is completely invisible. There is no way to diagnose this without external tools (ss -ltnp / netstat). A user would have no idea the problem is a port conflict. The extension should surface a human-readable error or warning notification when it cannot bind to the configured port.

Start by reproducing the conflict with port 3000 occupied, then trace the Show Preview (Internal Browser) command and the live server startup path. Inspect how the configured livePreview.portNumber is bound and how failures are reported. Done means a port conflict produces a clear notification or Live Preview Output entry, with coverage for the failing startup case.