docs: establish domain model, MVI spec, and environment reference

Capture the design work for the NixOS migration before any implementation:

- .claude/CONTEXT.md: domain glossary (Host, Module, Skeleton, Auto-loader,
  Enable convention, unstable/stable overlay)
- .claude/adr/0001-sops-nix-for-secrets.md: secrets tooling decision
- .claude/spec/laptop-mvi.md: frozen minimum-viable-install spec for neogaia

- reference/: read-only snapshot of the current CachyOS configs (secrets and
  state excluded), plus ENVIRONMENT.md profiling the live environment to guide
  replication

reference/home/.config/Trolltech.conf

@@ -0,0 +1,17 @@
+[qt]
+GUIEffects=none
+KDE\contrast=4
+KWinPalette\activeBackground=#272c31
+KWinPalette\activeBlend=#fcfcfc
+KWinPalette\activeForeground=#fcfcfc
+KWinPalette\activeTitleBtnBg=#202326
+KWinPalette\frame=#202326
+KWinPalette\inactiveBackground=#202428
+KWinPalette\inactiveBlend=#a1a9b1
+KWinPalette\inactiveForeground=#a1a9b1
+KWinPalette\inactiveFrame=#202326
+KWinPalette\inactiveTitleBtnBg=#202326
+Palette\active=#fcfcfc, #292c30, #393e43, #2e3337, #131516, #1c1f21, #fcfcfc, #ffffff, #fcfcfc, #141618, #202326, #0e0f10, #3daee9, #fcfcfc, #1d99f3, #9b59b6, #1d1f22, #000000, #292c30, #fcfcfc, #a1a9b1, #3daee9
+Palette\disabled=#686a6c, #272a2e, #383d42, #2d3136, #121415, #1b1d20, #606263, #ffffff, #6d6f72, #131517, #1f2124, #0d0e0f, #1f2124, #686a6c, #164160, #402b4c, #1c1e20, #000000, #292c30, #fcfcfc, #42464a, #1f2124
+Palette\inactive=#fcfcfc, #292c30, #393e43, #2e3337, #131516, #1c1f21, #fcfcfc, #ffffff, #fcfcfc, #141618, #202326, #0e0f10, #1b4155, #fcfcfc, #1d99f3, #9b59b6, #1d1f22, #000000, #292c30, #fcfcfc, #a1a9b1, #1b4155
+font="Noto Sans,14,-1,5,400,0,0,0,0,0,0,0,0,0,0,1,,0,0"