Add reference-based multi-source metrics and prepare 2.8.0 (#139)

[chammoru]

Summary

Closes #139. Deliver the user-reviewed Windows MFC reference-comparison feature after merged theme PR #138. This PR targets updated origin/master; integrating #138's merge commit produced no content changes to the verified feature tree. No Qt, arbitrary-pair or 2×2 layout redesign.

• A is the fixed reference; B/C/D keep stable source slots. Two/three/four loaded sources yield one/two/three independent PSNR, SSIM and real ONNX LPIPS result sets, including synchronized ROI scores.
• Compact current results sit directly below the actual B/C/D panes and track splitter widths. A shows noninteractive Reference/frame. Do not repeat source filenames or default RGB channel/detail captions; tooltips retain full paths, basis, channels, resolutions and scope. Reuse the existing whole-image RGB metric rather than averaging dB values or candidate scores.
• Actual independent frame indices are explicit, including Unaligned. Candidate-only seeks/reloads preserve other current scores, ROI and request identities. A bounded latest-wins pending slot per pair prevents repeated/stale requests from cancelling or starving unrelated pairs.
• Pair-specific valid ranges, generation keys, RGB/YUV strategies, caches and progress avoid truncation by a short candidate or padding unavailable frames. A coordinated worker decodes the reference once per aligned frame; LPIPS shares the existing engine and serialized model/session work.
• Up to three separate sequence graphs share the frame viewport; click/zoom/collapse and active-pair inspection retain other results and analysis state. Timeline has up to four lanes and extends to the longest loaded source.
• Preserve useful image area in small high-DPI windows: measure current source controls, shrink/scroll graph and result panels before exhausting the canvas, and clamp negative heights. This fixes the real 175% native acceptance failure without bypassing its assertion.
• Buffer pair/result controls and clear empty comparison views with theme colors, completing the shared painting audit started in Add Viewer-controlled shared Windows themes (#118) #138.
• Reconcile Windows UI redesign: Make Comparator source roles and filenames clear #129–Windows UI redesign: Make sequence analysis graphs contextual and readable #131's superseded A/B-only assumptions without closing their remaining independent design work. Update the user guide, Store copy and concise single-line 2.8.0 release notes.

Verification

• Local final CoreRegressionTests and WindowsUiTypographyTests pass. The layout allocator is checked at 5 DPI inputs × 5 text factors × 6 heights; buffer/menu checks retain warmed GDI 46/46.
• Both ordinary Viewer and Comparator Release/x64/v143 builds pass using the repository's default solution paths. Local version generation remains 0.0.0-dev.
• Real MFC Comparator integration passes 690 checks at each native 100/125/150/175% after the layout fix. Includes deterministic separate-pair equivalence, identity/infinity, real full/crop LPIPS for both backends, unequal frame domains, mixed RGB/YUV, independent current seeks/reloads, per-pair coalescing/cancellation and actual HWND paint/accessibility/layout behavior.
• Full Viewer integration passes 830 and startup 39 checks at native 125/150/175%, with media/capture/thumbnail/GPU/playback/recycle regressions retained.
• Actual Windows System Light/Dark and Night sky contrast transitions preserve loaded source/frame/ROI/current scores; native fallback scrollbar mouse/keyboard works. All active OS/app settings are restored. User reviewed the ordinary four-video UI and authorized separate merges and 2.8.0 release.

Limit disclosed before approval: native 200% is not in this monitor's ordinary scale list and was not applied through custom scaling. 192-DPI calculation tests pass but are not relabelled as a native 200% run. One PC/contrast scheme and native text factor 1.000 do not establish every OS or mixed scaling combination.

Evidence: comparison verification, actual OS acceptance.

Release notes are under the dated 2.8.0 section (1260 characters, below the Store workflow's 1500-character limit). The later tagged Actions workflow is the final packaging/signing/GitHub Release/Store authority and will run asynchronously; no workflow-completion claim is made by this PR. Existing user-owned untracked design files are excluded.

한국어

#138 테마 PR을 먼저 병합한 최신 master에 별도 #139 기능을 올립니다. A를 기준으로 B/C/D 각각의 수치·ROI·그래프와 4개 Timeline 열을 지원합니다. 수치는 후보 패널 바로 아래에 간결하게 배치하며 C만 탐색·갱신하면 B/D 결과를 보존합니다. 실제 175% 작은 창 문제도 수정 후 동일 검사에서 통과했습니다. 두 앱 일반 빌드·핵심 검사와 실제 배율별 통합 검증을 통과했고, 200% 실화면 미검증 한계를 안내한 뒤 병합·2.8.0 릴리즈를 승인받았습니다.

[chammoru]

Final local delivery recheck: CoreRegressionTests and WindowsUiTypographyTests exit 0; default-path Viewer/Viewer.sln and Comparator/Comparator.sln ordinary Release/x64/v143 builds exit 0. The updated instrumented Comparator was rebuilt and run from the repository root after master integration: comparer-2.8.0-final-report.txt, exit 0, 690 PASS, final all-checks-passed marker, actual DPI 96 and useful narrow canvas 334×214. Integration of theme PR #138 changed no verified feature content. Local generated version is still 0.0.0-dev; user-owned untracked design files remain excluded. Native 200% limitations remain documented. User explicitly authorized merge and v2.8.0 release; tagged Actions packaging/signing/Store completion will be asynchronous, not waited on or claimed complete.