Quick Open ranking doesn't prioritize exact filename matches (unlike VS Code) #17921

Bug Description:

Quick Open (Go to File) doesn't prioritize exact filename matches the way VS Code does. When searching for a full/exact filename or path, files that only partially match (contain the search term as a substring) are ranked above the exact match — which gets buried below several unrelated results instead of appearing at the top.

Steps to Reproduce:

1. Open a Theia-based IDE and open Quick Open (Ctrl+P / Go to File).
2. Search using the exact path: packages/plugin-ext/src/main/browser/webview/webview.ts
3. Observe that the top results are partial/substring matches — e.g. electron-webview-widget-factory.ts, webview-context-keys.ts, webview-environment.ts, webview-frontend-preference-contribution.ts — while the exact match, webview.ts, does not appear at the top and requires scrolling to find.
4. Compare with VS Code: searching the same path returns webview.ts as the top (and only) result, since VS Code's ranking prioritizes exact filename matches.

Additional Information

• Operating System: Ubuntu 24.04.4 LTS (WSL2, running on Windows)
• Theia Version: @theia/core 1.73.0 (branch feature/unified-logging-part-2, commit 4ce5b9451)
• Note: An earlier version of this issue described this as a duplicate-results problem caused by an unexcluded dev/theia directory in the workspace — that turned out to be expected behavior (workspace root was scoped to home directory, correctly indexing two real checkouts). The actual underlying issue is the ranking behavior described above, which was present in the same search but obscured by the duplicate-directory confusion.
• Comparison: VS Code correctly surfaces the exact filename match at the top; Theia's fuzzy matcher ranks substring matches equally or higher (see attached screenshot).

Theia

VS Code