Live Preview can generate malformed URLs for absolute links and workspace paths

[dknn]

Bug

Live Preview can generate malformed preview URLs in two related cases:

1. Absolute HTTP(S) URLs can be prefixed with the preview host, producing URLs such as http://127.0.0.1:3000/http://example.test/page.html and, depending on the caller-provided value, http://http://....
2. Workspace-relative paths can be returned without a leading slash when the workspace root already ends with a path separator, producing a URL with the path joined directly after the port, e.g. http://127.0.0.1:3000index.html.

Expected behavior

• Absolute http:// and https:// URLs should be preserved as absolute URLs.
• Preview paths served from the local Live Preview host should include / after the port.

Actual behavior

• Absolute HTTP(S) URLs can be treated as local preview paths and receive another host/protocol prefix.
• In trailing-separator workspace cases, the path can be appended immediately after the port.

Environment

• Extension: Live Preview 0.4.18 local build, also observed while testing 0.4.19 install behavior
• OS: Windows
• Workspace type involved in repro: local/network workspace path where the resolved workspace root can include a trailing separator

Proposed fix

I have a small fix and regression tests ready in branch dknn:codex/fix-live-preview-url-normalization:

• preserve absolute http:// and https:// URL inputs in WebviewComm.constructAddress
• ensure Connection.getFileRelativeToWorkspace returns a leading slash for workspace-relative paths