feat: flake inputs/outputs and settings.nix entry point

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

settings.nix

@@ -0,0 +1,39 @@
+# Omnixient User Settings
+#
+# This is the ONE file every adopter edits to make Omnixient their own.
+# Everything machine- or person-specific is funnelled through here and
+# threaded into the modules — you shouldn't need to hunt through the tree.
+#
+# (Your hardware scan is the only other per-machine piece: see
+#  hosts/<name>/hardware-configuration.nix and docs/getting-started.md.)
+{
+  # --- Identity ---
+  user = "padreug"; # your Linux username (the home dir, primary account)
+  gitName = "Padreug"; # git author name
+  gitEmail = "padreug@aiolabs.dev"; # git author email
+  hostName = "omni"; # machine hostname == hosts/<hostName>/ directory
+  # Find yours with `timedatectl list-timezones`, or the "TZ identifier"
+  # column at https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
+  timeZone = "Europe/Paris"; # e.g. "America/New_York", "Asia/Tokyo"
+
+  # --- Desktop theme ---
+  # One of modules/themes/*.nix (without the .nix). Switch at runtime with
+  # `omni-theme <name>`; this is just the default a fresh build boots with.
+  theme = "gruvbox";
+
+  # --- SSH public keys ---
+  # Authorized to log into this machine's `user` account over SSH. Paste
+  # the contents of your ~/.ssh/id_ed25519.pub (or .pub of choice). Empty
+  # list = no key-based SSH logins.
+  sshKeys = [
+    # "ssh-ed25519 AAAAC3Nza... you@host"
+  ];
+
+  # --- NixOS state version ---
+  # CRITICAL: set this to the NixOS release you FIRST installed with, and
+  # then NEVER change it. It pins stateful defaults (databases, etc.) for
+  # backwards compatibility; bumping it on an existing system can silently
+  # break data. It is NOT your current NixOS version. On a fresh install,
+  # use the release you installed from (e.g. "24.05", "24.11", "25.05").
+  stateVersion = "24.05";
+}