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/kwinoutputconfig.json

@@ -0,0 +1,93 @@
+[
+    {
+        "data": [
+            {
+                "abmLevel": 0,
+                "allowDdcCi": true,
+                "allowSdrSoftwareBrightness": false,
+                "autoBrightnessCurve": [
+                    0,
+                    0,
+                    0,
+                    0,
+                    0,
+                    0,
+                    0,
+                    0,
+                    0,
+                    0,
+                    0
+                ],
+                "autoRotation": "InTabletMode",
+                "automaticBrightness": false,
+                "brightness": 1,
+                "colorPowerTradeoff": "PreferEfficiency",
+                "colorProfileSource": "sRGB",
+                "connectorName": "eDP-1",
+                "customModes": [
+                ],
+                "detectedDdcCi": false,
+                "edidHash": "5f3fe94f152da0c618ae754a160d08df",
+                "edidIdentifier": "AUO 23341 0 0 2018 0",
+                "edrPolicy": "always",
+                "hdrColorProfileSource": "EDID",
+                "hdrIccProfilePath": "",
+                "highDynamicRange": false,
+                "iccProfilePath": "",
+                "maxBitsPerColor": 0,
+                "mode": {
+                    "flags": 1,
+                    "height": 1080,
+                    "refreshRate": 60033,
+                    "width": 1920
+                },
+                "overscan": 0,
+                "rgbRange": "Automatic",
+                "scale": 1,
+                "sdrBrightness": 200,
+                "sdrGamutWideness": 0,
+                "sharpness": 0,
+                "transform": "Normal",
+                "uuid": "3f5a91e5-1c16-44d8-a5f5-b5854daa57be",
+                "vrrPolicy": "Never",
+                "wideColorGamut": false
+            }
+        ],
+        "name": "outputs"
+    },
+    {
+        "data": [
+            {
+                "lidClosed": false,
+                "outputs": [
+                    {
+                        "enabled": true,
+                        "outputIndex": 0,
+                        "position": {
+                            "x": 0,
+                            "y": 0
+                        },
+                        "priority": 1,
+                        "replicationSource": ""
+                    }
+                ]
+            },
+            {
+                "lidClosed": true,
+                "outputs": [
+                    {
+                        "enabled": true,
+                        "outputIndex": 0,
+                        "position": {
+                            "x": 0,
+                            "y": 0
+                        },
+                        "priority": 0,
+                        "replicationSource": ""
+                    }
+                ]
+            }
+        ],
+        "name": "setups"
+    }
+]