feat: create new home/ directory structure for profile-based config

New structure:
- home/base/        - Always loaded (shell, cli-tools, secrets)
- home/coding/      - Profile-independent dev tooling (editor, lsp, git, agents)
- home/profiles/    - Freely combinable profiles (gaming, media)
- home/desktop/     - Desktop-only (wm, apps, theme)
- home/server/      - Minimal server stub

Migration sources:
- home/features/cli/ → home/base/{shell,cli-tools,secrets}
- home/features/desktop/hyprland,wayland,rofi → home/desktop/wm/
- home/features/desktop/obsidian,office,webapps,crypto → home/desktop/apps/
- home/features/desktop/fonts,theme,wallpapers → home/desktop/theme/
- gaming.nix split → home/profiles/gaming/{steam,gamescope}
- media.nix split  → home/profiles/media/{obs,ffmpeg,yt-dlp,kdenlive,handbrake}

Option namespaces updated:
- features.cli.*  → base.shell.* / base.cliTools.* / base.secrets
- features.desktop.* → desktop.wm.* / desktop.apps.* / desktop.theme.*
- features.desktop.gaming → profiles.gaming.*
- features.desktop.media  → profiles.media.*

Verified: nix flake check passes (warnings only)

home/coding/git/git.nix

@@ -0,0 +1,41 @@
+# Git configuration with signing, aliases, and global ignore.
+# Identity and host-specific SSH keys are set per-host in home/m3tam3re/.
+{
+  lib,
+  pkgs,
+  ...
+}:
+with lib; {
+  programs.git = {
+    enable = true;
+    signing.format = null;
+    settings = {
+      user = {
+        name = lib.mkDefault "m3tam3re";
+        email = lib.mkDefault "p@m3ta.dev";
+      };
+      core.excludesfile = "~/.gitignore_global";
+      init.defaultBranch = "master";
+      alias = {
+        st = "status";
+        logd = "log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit";
+      };
+    };
+  };
+
+  programs.difftastic.enable = true;
+
+  programs.jujutsu = {
+    enable = true;
+    settings = {
+      user = {
+        email = "m@m3tam3re.com";
+        name = "Sascha Koenig";
+      };
+    };
+  };
+
+  home.packages = with pkgs; [
+    lazygit
+  ];
+}