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/kwinrc

@@ -0,0 +1,60 @@
+[Desktops]
+Id_1=4c183a08-13bd-40a0-8131-12584ba0b0c0
+Id_2=b20e6cf5-12e6-44c9-b8f1-0bb5a5e2307a
+Id_3=77ff2787-e9df-4539-b009-8da2084b3ba0
+Id_4=f4bc9302-9b20-4cbb-b73b-4cfecba52889
+Id_5=e0032b5e-9f48-4219-8800-152a21b01604
+Id_6=a3ac962a-66e0-4cfe-a9ca-a789eae23a3a
+Id_7=6ecab170-20d2-4383-b152-0d443d77b8ad
+Id_8=ba6489cf-4f95-4786-af9f-3d742e17e6c5
+Id_9=5f9b8e88-3740-4d2c-9ac5-e76e072606f4
+Number=9
+Rows=1
+
+[Effect-zoom]
+InitialZoom=4.136880223300198
+
+[Plugins]
+zoomEnabled=false
+
+[Tiling][4c183a08-13bd-40a0-8131-12584ba0b0c0][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][5f9b8e88-3740-4d2c-9ac5-e76e072606f4][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][6ecab170-20d2-4383-b152-0d443d77b8ad][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][77ff2787-e9df-4539-b009-8da2084b3ba0][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][a3ac962a-66e0-4cfe-a9ca-a789eae23a3a][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][b20e6cf5-12e6-44c9-b8f1-0bb5a5e2307a][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][ba6489cf-4f95-4786-af9f-3d742e17e6c5][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][e0032b5e-9f48-4219-8800-152a21b01604][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Tiling][f4bc9302-9b20-4cbb-b73b-4cfecba52889][3f5a91e5-1c16-44d8-a5f5-b5854daa57be]
+padding=4
+tiles={"layoutDirection":"horizontal","tiles":[{"width":0.25},{"width":0.5},{"width":0.25}]}
+
+[Windows]
+RollOverDesktops=true
+
+[Xwayland]
+Scale=1