VC3D: add non-destructive surface view orientation controls

[LubuSeb]

Closes #370.

Issue: #370

Reproduction

VC3D currently has saved-surface rotate/flip actions, but the active surface-view image itself cannot be rotated or flipped non-destructively for inspection. Issue #370 asks for rotate and horizontal flip controls so users can inspect a surface or ink prediction from a different orientation without mutating saved surface geometry.

Changes

• Added non-destructive active surface-view orientation state.
• Added viewer shortcuts for rotating the active surface view clockwise and flipping it horizontally.
• Used Ctrl+R for rotate because plain r is already bound to "Center focus on cursor"; used plain f for horizontal flip to match the issue suggestion where no existing plain-key conflict was found.
• Applied the orientation consistently through render dimensions, surface/view coordinate mapping, pan/zoom behavior, intersections, same-wrap annotation previews, and render-bench replay/recording state.
• Reset the orientation with the existing reset-view path and with the existing segmentation reset-on-surface-change path.

Scope / Minimality

This is focused on the active view only. It does not call or change the existing saved-surface rotate/flip commands, does not modify persisted surface geometry, and does not change unrelated VC3D controls or non-VC3D subprojects.

Validation

• Ran git diff --check.
• Ran Dockerized VC3D release build with cmake --preset ci-release-gcc && cmake --build --preset ci-release-gcc using ghcr.io/scrollprize/villa/volume-cartographer:builder-ubuntu-26.04; it passed.
• Ran Dockerized VC3D test build with cmake --preset ci-tests-gcc && cmake --build --preset ci-tests-gcc && ctest --preset ci-tests-gcc; it passed with 97/97 CTest tests.
• Reran cmake --build --preset ci-tests-gcc && ctest --preset ci-tests-gcc --output-on-failure through the same builder image; it passed.
• Ran a Dockerized Xvfb GUI startup smoke test with timeout 8s xvfb-run -a build/ci-tests-gcc/bin/VC3D; VC3D started, logged normal viewer initialization, and stayed alive until the timeout.

Known Limits / Non-goals

• I did not run a manual interactive desktop walkthrough in this environment.
• This does not add a toolbar/menu action; it only adds keybind-backed view controls and help text.
• This does not change prize rules or make any progress-prize claim in the PR.

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