ChromIQ v3.13.0-beta.4

Fixes and polish for the colour-file loading added in beta-3, from Knut's
testing with real scanner-target files.

🐛 Fixed

• Loaded reference colours are no longer dim / squeezed. CIE files describe
  reflective targets whose media white sits well below a perfect white (e.g.
  Hutchcolor ≈ 77%), so rendering them absolutely made everything look dark
  and the 3D cube collapse toward a gamut shape. Loading is now media-relative
  by default — the target's white maps to display white, so the colours fill the
  cube and read naturally.
• The live 3D cube now reflects pasted / loaded / single colours, not only
  the generated sets. (Seed-from-targen is still previewed only after generating.)
• "Blank canvas" clears the preview (and Update preview now works on an
  empty chart) instead of leaving the previous chart's image behind.
• The New chart / Add window no longer slips behind the editor after the
  file dialog closes.
• Colours loaded into the Add window are de-duplicated (near-identical ones
  spaced apart) so they don't run together and hurt readability.

✨ New / changed

• Custom spacer colours gained white and black swatches (5 accents → 7),
  giving the engine a strong high-contrast separator against very light or very
  dark patches.
• The spacer-colour pickers now use ChromIQ's own colour dialog (hex + RGB/HSV),
  matching the rest of the app, instead of the OS colour panel.
• Dark-mode standard tabs (Settings) now match the roomier light-mode tabs.

📝 Notes

• Open follow-ups before 3.13.0 final are unchanged from beta-3: translations of
  the new strings, real-hardware print+measure verification, multi-strip
  instruments, and the planned scanner-target workflow (#95 / #97 / #98).
• Thanks again to Knut Georg Larsson for the detailed testing and sample
  files.

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Installation (Linux, beta): Download the tarball for your architecture (x86_64 for most desktops/laptops, aarch64 for ARM systems like Raspberry Pi 4/5). Extract with tar xzf ChromIQ-Linux-*.tar.gz, then run ./ChromIQ/ChromIQ. Requires ArgyllCMS — install via your package manager (sudo apt install argyll) or from argyllcms.com/downloadlinux.html.