Show Browse paths and preserve the view on navigation failure (#121)

[chammoru]

Closes #121.

Summary

• Show the committed Browse folder in a distinct single-line, read-only header above compact rows and gallery grids. Use neutral Light/Dark surfaces, medium Pretendard and one thin bottom separator, preserving full-path accessibility, tooltip, keyboard focus and copying.
• Prepare directory metadata asynchronously before committing path/list changes. Preserve the previous folder, selection, scroll, image and playback on errors; report explicit failures, suppress background dialog spam and discard superseded results.
• Retain existing parent/drive/UNC navigation, watchers, thumbnail caches, source interpretation and safe recycle interactions. No Comparator or Qt product UI changes.
• Make the existing Comparer wheel/menu regression independent of desktop-specific initial fit ratios. Explicitly test the legitimate 100-percent fit stop and require strict zoom directions from a controlled 200-percent starting point; production zoom behavior is unchanged.
• Prepare v2.8.3 changelog and Store description. Keep the local version at 0.0.0-dev; tagged Actions builds set the release version.

Approval and verification

The user reviewed the ordinary Viewer, approved the header appearance, and explicitly requested commit, push and release on 2026-10-19. This PR is no longer awaiting design approval.

• Final actual Viewer integration: 1,925 PASS, exit 0; focused Browse/navigation/interaction: 397 PASS, exit 0.
• CoreRegressionTests and WindowsUiTypographyTests passed; GDI 55 before / 55 after.
• Ordinary and instrumented Viewer and Comparator Release/x64/v143 builds passed; final Comparer actual integration: 780 PASS, exit 0, including the 100-percent fit stop, actual wheel direction/menu geometry and existing source/metric/LPIPS regressions.
• Native ordinary-window review confirmed the distinct location band, full accessible path and focus/Escape behavior without changing the sample image or 100.0-percent zoom.

The previous Gallery CI failure was the Comparer wheel assertion's assumption that every zoom-out must change the scale, even at the valid fit/100-percent stop. The test now isolates menu-paint behavior from that limit without relaxing its directional checks.

Verification and limitations. Actual OS DPI/high-contrast transitions and physical drive disconnects were not performed; enlarged fonts, theme painting and injected provider errors are not claimed as equivalent to those manual tests.

한국어 요약

사용자가 현재 경로 헤더의 디자인을 확인하고 커밋·푸시·릴리즈를 승인했습니다. 경로를 중성 배경·중간 굵기·얇은 아래 구분선으로 목록과 구분하고, 이동 실패 시 기존 화면을 보존합니다. 전체 경로 복사와 기존 폴더·드라이브 이동은 유지합니다. v2.8.3은 Windows 패치 릴리즈이며 로컬 개발 버전은 그대로입니다. 릴리즈 태그를 푸시한 뒤 Actions 완료를 계속 기다리지 않고 실행 링크를 안내합니다.