feat(github): add auto-conventional-commit hook with opencode integration

- Add prepare-commit-msg git hook that generates conventional commit messages
- Modularize fish configuration with separate conf.d files
- Convert configuration files from .text to .source format for structured data
- Add sops-nix SOPS configuration with explicit secret definitions
- Upgrade age identity to single key file management approach
- Add system activation script for age key management
- Generate .sops.yaml for SOPS creation rules
- Restructure README.md with improved table and cleaner formatting
- Refactor config files to use pkgs.formats.json/toml generators
- Implement YAML format for ashell and walker service configurations
- Update SSH config source to use sops secrets
- Convert zed and other config files to use structured .source format

hosts/default.nix

@@ -5,6 +5,7 @@
 }: let
   # shorten paths
   inherit (inputs.nixpkgs.lib) nixosSystem;
+  lib = inputs.nixpkgs.lib;
   # Server uses its own pinned 24.05 nixpkgs (kept isolated from the laptop's unstable)
   nixosSystem24 = inputs.nixos-24-05.lib.nixosSystem;
   unstablePkgs = import inputs.nixpkgs-unstable {system = "x86_64-linux";};
@@ -23,7 +24,7 @@
     "${mod}/services/gnome-services.nix"
     "${mod}/core/limine.nix"
     "${home}"
-    inputs.agenix.nixosModules.default
+    inputs.sops-nix.nixosModules.sops
   ];
 in {
   flake.nixosConfigurations = {
@@ -50,6 +51,35 @@ in {
         ];
     };
 
+    # Laptop UEFI: explicit UEFI boot mode
+    laptop-uefi = nixosSystem {
+      inherit specialArgs;
+      modules =
+        laptop
+        ++ sharedModules
+        ++ [
+          "${mod}/services/location.nix"
+          ({ config, ... }: {
+            boot.loader.limine.bootMode = "uefi";
+          })
+        ];
+    };
+
+    # Laptop BIOS: explicit BIOS boot mode
+    laptop-bios = nixosSystem {
+      inherit specialArgs;
+      modules =
+        laptop
+        ++ sharedModules
+        ++ [
+          "${mod}/services/location.nix"
+          ({ config, ... }: {
+            boot.loader.limine.bootMode = "bios";
+            boot.loader.limine.biosDevice = "/dev/nvme0n1";
+          })
+        ];
+    };
+
     # Server: severijnse.eu (Hetzner) — fully isolated under servers/hetzner/.
     # Uses nixos-24.05 + disko + sops-nix and does NOT inherit the laptop's shared modules.
     hetzner = nixosSystem24 {