[BUG] VSCode extension: markdown links to directories in chat are dead (clicking does nothing), though the system prompt instructs Claude to emit them

Environment: Claude Code VSCode extension (native), macOS 15.5 (Darwin 25.5.0), workspace opened at ~

Description:
In the VSCode extension chat panel, markdown links to files work correctly — relative and absolute paths, #L42-L51 line ranges (open with the range highlighted), and web URLs. But markdown links whose target is a directory render as normal clickable links and then silently do nothing when clicked — with or without a trailing slash, relative or absolute.

Repro:

1. Open the extension with any workspace.
2. Have Claude emit [some-dir/](some-dir/) pointing at an existing directory, and [some-file.md](some-dir/some-file.md) as a control.
3. The file link opens in the editor; the directory link does nothing (no error, no Explorer reveal).

Why it matters: the extension's injected system prompt explicitly instructs Claude to use this form — "For folders: [src/utils/](src/utils/)" — so Claude reliably produces links that reliably fail for users. Either the click handler should reveal the folder in the Explorer, or the system prompt guidance should drop the folder-link instruction.