Show "did you mean" suggestions live, before Enter, when the query matches nothing

[dawsbot]

Problem

The extension has a nice "did you mean" fallback (getClosestMatches in src/closest-match.ts: subsequence + Damerau-Levenshtein), but in practice users almost never see it.

findRelativePath() in src/extension.ts has two picker paths:

• Quick-filter path (allowQuickFilter — the common case, any workspace under relativePath.searchCountLimit, default 10,000 files): uses window.showQuickPick. VS Code does the live filtering, and when the typed value matches nothing it shows its native empty state. getClosestMatches is never called here.
• Input-box path (>10k files): the closest-match fallback runs, but only after the user presses Enter.

So while you're typing and there are zero matches, you just get an empty list. The "looks like" / Levenshtein suggestions should kick in as soon as matches hit zero, without pressing Enter.

Expected

In the quick-filter picker, when the current query matches no file, show the getClosestMatches suggestions live (after a short debounce) under a "did you mean" separator, without requiring Enter.

Notes

• window.showQuickPick is fire-and-forget with no live-typing hook; this needs a managed window.createQuickPick() + onDidChangeValue.
• Keep VS Code's native fuzzy filtering/highlighting on for the happy path; only inject suggestions when the query would otherwise be empty (i.e. it is not a subsequence of any candidate's relative path).