fix(mac): regenerate app icons for consistent sizing across all surfaces

[zhangzhend0ng]

Description

Follow-up to the Orca icon update in #858/#867. After auditing every icon surface shipped by those PRs, three assets still carried inconsistent geometry:

1. Icon.icns / resources/images/Snapmaker_Orca.icns (app bundle icon)

The icns regenerated in #858 had three defects, verified by parsing every chunk:

Chunk	Size	Tile ratio
icp4/icp5	16/32px	1.00 (full-bleed)
icp6	64px	0.91
ic07–ic10	128–1024px	0.89

• Internal inconsistency: the 16/32px frames were full-bleed while 64px+ carried a 0.89 tile ratio, so the icon visibly changed size between contexts that pick different representations (Dock magnification, Cmd-Tab, Finder list vs icon view).
• Dropped @2x variants: the previous icns contained ic12/ic13 retina variants; the Feature/update orca icon #858 file dropped all of ic11–ic14.
• Off-center master: the 1024px source frame had asymmetric margins (81px top vs 33px bottom).

Fixed by extracting the 1024px master, normalizing it to the Apple icon grid (824/1024 tile, centered — matching the 0.805 ratio the pre-#858 icns already used), and regenerating via iconutil from a uniformly-composed iconset. All sizes now share the same 0.805 layout and ic11–ic14 are restored.

2. Snapmaker_Orca-mac_256px.ico (macOS Dock taskbar icon, MainFrame.cpp)

#858's "regenerate full-bleed to fix smaller taskbar icon" commit only regenerated the Windows Snapmaker_Orca.ico (all 6 sizes full-bleed ✓) — the -mac_256px.ico used by wxTBI_DOCK on macOS was missed and kept its baked-in padding, so the custom Dock icon rendered smaller than the bundle icon. Re-exported from the same normalized 256px frame so both surfaces match.

3. splash_app_icon.svg (splash screen logo, GUI_App.cpp)

The splash still used an early, noticeably thinner version of the new glyph (last touched 2026-06-18, before the icon redesign). No vector source of the final glyph exists in the repo, so the glyph was retraced from the 1024px icon master (directed-edge contour tracing + Ramer–Douglas–Peucker simplification, 1560 → 514 points). Tile structure unchanged (#171717, rx=20, 140 viewBox); only the glyph path was replaced. Pure rect + M/L/Z path, fully compatible with nanosvg.

Screenshots/Recordings/Graphs

Verification of the regenerated icns (every chunk parsed and measured):

new Icon.icns:
  icp4/icp5/ic04/ic05 (16/32px):  ratio 0.805  (was 1.00)
  icp6/ic11/ic12     (64px):      ratio 0.812  (was 0.91)
  ic07/ic08/ic09/ic10/ic13/ic14:  ratio 0.805  (was 0.89)
  ic11–ic14 @2x variants:         restored     (were missing)

iconutil -c iconset round-trip parses cleanly; both icns copies are byte-identical (md5).

Tests

• ./build_release_macos.sh -sx builds cleanly (arm64, Ninja Multi-Config, exit 0)
• Verified all three replaced assets land in the built .app bundle with correct md5, and CFBundleIconFile → Icon.icns resolves
• NSImage renders the new icns at 16/32/64/128px pixel-identical to the source iconset (avg diff 0.0) — confirms all chunk types (incl. iconutil's raw-ARGB ic04/ic05) decode correctly
• Splash glyph fidelity: soft-mask IoU vs the 1024px master glyph = 0.715 (the replaced file scored 0.508 with the same methodology), strong pixel disagreement 1.77%
• Packaged Snapmaker_Orca_macos_arm64_c76c3d5.dmg (170MB), mounted and verified bundle contents + adhoc signature
• Document-type icons (CFBundleTypeIconFile = images/Snapmaker_Orca.icns for .3mf) resolve to the clean icon via NSWorkspace.icon(forFile:)

Note for reviewers/testers: if a Mac that had many dev builds or DMG-launched copies of the app shows a noisy .3mf document icon, that is stale/dangling LaunchServices registration on that machine (not this asset) — re-registering the installed app and clearing ~/Library/Caches/com.apple.iconservices* fixes it.