feat(nixos): consolidate hosts into a shared flake

Manage T450s, X1EG2 and Framework 13 from pinned NixOS inputs while retaining
machine-specific storage and hardware configuration.

Changes:

Shared Configuration:
- Extract common, KDE, desktop, development and Steam modules
- Share Emacs, VS Code, htop, DevOps tools and Docker across hosts
- Remove obsolete apps and global project language runtimes

Framework:
- Import the 11th-generation Intel hardware profile
- Enable Steam and ZFS with tookland/home mounted at /home
- Document manual ext4 root and ZFS installation steps
- Require installer-generated hardware configuration before installation

Validation:
- Evaluate both ThinkPads and Framework with test hardware
- Check Nix syntax, formatting and whitespace

flake.lock

@@ -0,0 +1,65 @@
+{
+  "nodes": {
+    "nixos-hardware": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1791128201,
+        "narHash": "sha256-rlsYY/Dg/LhbIj51Aa6TLvRpZeb3KZgUTd7llQ5XcJE=",
+        "owner": "NixOS",
+        "repo": "nixos-hardware",
+        "rev": "31cc5f4d9b9ba601071e8b8504601b9b176e2756",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixos-hardware",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1791254437,
+        "narHash": "sha256-qMSsgG+9tIdx282dMqGuJAUK3t6F36clM6efd0rXfes=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "b25309931cfda5f0b8805f462a29897eeae50168",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-26.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1791260994,
+        "narHash": "sha256-Miqqk/ammqnTUxaoCyvtwoPeLbI1ksFyLxi/CazZpWY=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "151fa4e8ddfdd8dd25d945ad94ed54a13de9f6e4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixos-hardware": "nixos-hardware",
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-unstable": "nixpkgs-unstable"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}