listWorkspaceFiles() walks a directory recursively, returning
[{path, name}] for files matching a configurable extension allowlist.
Skips hidden dirs, node_modules, dist/build/coverage, and walks past
permission-denied subdirs instead of throwing. Default allowlist is
markdown variants + .txt; default maxResults caps pathological
workspaces at 2000 entries.
Wired through 'quick-switcher:list-files' invoke channel + a
quickSwitcher.listFiles() convenience method on the preload bridge.
Main-process errors collapse to [] rather than crashing the overlay.
16 new tests covering flat dirs, recursion, skip lists, custom
extensions, maxResults cap, and validation errors.
Amit Haridas