Establish project foundation: domain model, MVI spec, 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/nvim/lazy-lock.json

@@ -0,0 +1,13 @@
+{
+  "diffview.nvim": { "branch": "main", "commit": "4516612fe98ff56ae0415a259ff6361a89419b0a" },
+  "gitsigns.nvim": { "branch": "main", "commit": "eb60cc7b94c46005237fd34170d76f3a089a90aa" },
+  "lazy.nvim": { "branch": "main", "commit": "306a05526ada86a7b30af95c5cc81ffba93fef97" },
+  "neogit": { "branch": "master", "commit": "6fc2fa890bd2031ed999c074daab0fb4feff20a5" },
+  "nord.nvim": { "branch": "main", "commit": "87394d4fc35c901bbe38326a78d31ab1ead826b6" },
+  "nvim-treesitter": { "branch": "master", "commit": "cf12346a3414fa1b06af75c79faebe7f76df080a" },
+  "oil.nvim": { "branch": "master", "commit": "b73018b75affd13fa38e2fc94ef753b465f770d7" },
+  "plenary.nvim": { "branch": "master", "commit": "74b06c6c75e4eeb3108ec01852001636d85a932b" },
+  "render-markdown.nvim": { "branch": "main", "commit": "f422cb5c6855f150e2ddcfaf44e7157b98b34f6a" },
+  "snacks.nvim": { "branch": "main", "commit": "882c996cf28183f4d63640de0b4c02ec886d01f2" },
+  "which-key.nvim": { "branch": "main", "commit": "3aab2147e74890957785941f0c1ad87d0a44c15a" }
+}