Enable breadcrumbs for unsaved (untitled) files

[Copilot]

Breadcrumbs were silently suppressed for untitled editors because BreadcrumbsControl.update() gated on IFileService.hasProvider(uri) — which is false for the untitled:// scheme. Opening a new file and setting a language mode yielded no breadcrumbs at all, even though outline/symbol data was available.

Changes

• breadcrumbsControl.ts — Exempt untitled:// URIs from the file-provider guard so they reach the breadcrumbs pipeline:

  // before
  if (!uri || !this._fileService.hasProvider(uri)) {
  // after
  if (!uri || (!this._fileService.hasProvider(uri) && uri.scheme !== Schemas.untitled)) {

  BreadcrumbsModel._initFilePathInfo() already returns an empty path for untitled:// URIs, so no file/folder crumbs appear — only language symbols from the outline.

• breadcrumbModel.test.ts — Add test asserting an untitled URI produces zero file-path elements.