[cherry-pick] themes: fix match highlight contrast in focused quick pick rows (2026 themes)

[vs-code-engineering]

Cherry-pick of #314117 from main.

#313740 increased the contrast of the focused quick pick row in the 2026 Dark and 2026 Light themes by switching the focus background to a saturated blue and the row foreground/icon foreground to white. This unfortunately caused a regression for search match highlights on the focused row: the matched substring still rendered using list.highlightForeground (blue), producing blue text on a blue background.

This PR adds list.focusHighlightForeground: #FFFFFF to both 2026 themes so match highlights on the focused row are rendered in white — matching the focused row's foreground/icon colors. The original list.highlightForeground (blue) is preserved for unfocused rows, retaining the prior accessibility fix.

Fix:

Before:

Verified against

1. Quick pick background (unfocused rows) — blue match highlight remains legible ✓
2. Focused quick pick row — white match highlight is legible against the saturated blue focus background ✓

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@TylerLeonhardt

Matched files:

• src/vs/platform/quickinput/browser/media/quickInput.css