feat(modules): users, scripts, menus, fastfetch, walker, cache, colors, bootstrap

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/cache.nix

@@ -0,0 +1,45 @@
+# Binary cache configuration.
+#
+# Substituters and trusted public keys for cache.nixos.org and
+# nix-community, plus a stub for the aiolabs cache (uncomment when
+# configured). Imported by every host that wants pre-built artifacts
+# instead of compiling from source.
+#
+# Why this exists as its own module: the optimize-deploys/unified flake
+# notes that host1/host3/host2 share ~90% of derivations, so the second
+# and third deploys would be near-instant once a cache is set up. Same
+# applies for the dev box rebuilds. Rather than scatter substituter
+# configuration across every host, define it once.
+#
+# Pushing to the cache is one Makefile target (`make cache`) — see the
+# top-level Makefile.
+
+{ ... }:
+
+{
+  nix.settings = {
+    substituters = [
+      "https://cache.nixos.org"
+      "https://nix-community.cachix.org"
+      # Uncomment when the aiolabs cache is configured.
+      # "https://aiolabs-nix.cachix.org"
+    ];
+
+    trusted-public-keys = [
+      "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      # Add the aiolabs cache public key here once we generate it:
+      #   cachix authtoken <token>
+      #   cachix create aiolabs-nix
+      # The public key is shown after `cachix create`.
+      # "aiolabs-nix.cachix.org-1:..."
+    ];
+
+    # Allow more substituters at runtime via `--option extra-substituters`
+    # without editing this file. Useful for one-off testing.
+    trusted-substituters = [
+      "https://cache.nixos.org"
+      "https://nix-community.cachix.org"
+    ];
+  };
+}