Update DMG layout for vertical background

[FuJacob]

Summary

Updates the release DMG to use the new vertical background asset at assets/release/dmg_background.png.

The source PNG is 1080x1520. The DMG script now treats it as 2x art and opens Finder at 540x760, which keeps the vertical installer compact enough to avoid the oversized scrolling feel. The app icon is centered above the arrows and the Applications shortcut is centered in the dashed drop target.

Validation

• python3 -m py_compile scripts/build_release_dmg.py -> exit 0
• sips --resampleHeightWidth 760 540 assets/release/dmg_background.png --out /tmp/tabby-normalized-dmg-background-small.png -> output PNG is 540x760
• python3 scripts/build_release_dmg.py --app-path /Users/jacobfu/Library/Developer/Xcode/DerivedData/tabby-fudilwczjhlrywbzrvmcjwzngjmh/Build/Products/Debug/tabby.app --output-path /tmp/Tabby-vertical-layout-test-small.dmg --background-path assets/release/dmg_background.png --volume-name TabbyTestSmall -> built styled DMG successfully
• hdiutil imageinfo /tmp/Tabby-vertical-layout-test-small.dmg -> confirmed UDZO compressed DMG
• git diff --check -> exit 0

Linked issues

None.

Risk / rollout notes

This renames the release background path from assets/release/dmg-background.png to assets/release/dmg_background.png; the release workflow and release docs were updated to match. The Finder window remains vertical, but is now much smaller than the first PR version.

Greptile Summary

This PR replaces the horizontal DMG installer background with a new vertical 1080×1520 asset, updating the Finder window dimensions and icon positions throughout the build script, workflow, and documentation.

• scripts/build_release_dmg.py: Window size changed from 960×640 to 540×760 (2× source-art convention), and both icon positions recentered for the vertical layout — app icon at (270, 280) and Applications shortcut at (270, 635).
• .github/workflows/release.yml / RELEASING.md: Background asset path renamed from dmg-background.png (hyphen) to dmg_background.png (underscore) and verification prose updated to describe the new above/below flow instead of left/right.
• assets/release/: Old horizontal PNG deleted, new vertical PNG added.

Confidence Score: 5/5

Safe to merge — all changed files are DMG packaging infrastructure with no runtime app logic, and the asset rename is consistently applied across the workflow, script, and docs.

The layout constants in the script are internally self-consistent (2× source art at 1080×1520 maps cleanly to a 540×760 Finder window), the old asset reference has been fully replaced with the new underscore filename everywhere it appeared, and the author validated the full build end-to-end before opening the PR.

No files require special attention.

Important Files Changed

Filename	Overview
scripts/build_release_dmg.py	Updated WINDOW_WIDTH/HEIGHT to 540×760 and recentered both icon positions for the new vertical background; the 2× source-art math is self-consistent and the sips argument order (height then width) is correct.
.github/workflows/release.yml	Single filename change from dmg-background.png (hyphen) to dmg_background.png (underscore) to match the new committed asset; no logic changes.
RELEASING.md	Updated background asset filename and adjusted verification prose from left/right layout to above/below vertical layout.
assets/release/dmg_background.png	New 1080×1520 vertical background asset; replaces the deleted dmg-background.png (horizontal layout).
assets/release/dmg-background.png	Deleted old horizontal background asset; superseded by dmg_background.png.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["release.yml\n--background-path assets/release/dmg_background.png"] --> B["build_release_dmg.py"]
    B --> C["require_existing_path(background_path)"]
    C --> D["normalize_background_image()\nsips --resampleHeightWidth 760 540\n1080×1520 → 540×760"]
    D --> E["write_settings_file()\nwindow_rect = 540×760\nAPP_ICON @ (270, 280)\nAPPS_ICON @ (270, 635)"]
    E --> F["dmgbuild → Tabby.dmg\nVertical installer layout"]
    F --> G["codesign --verify\nspctl --assess"]

Loading

_{Reviews (2): Last reviewed commit: "Shrink vertical DMG window" | Re-trigger Greptile}