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/desktop/default.nix

@@ -0,0 +1,125 @@
+# Desktop environment aggregator — only loaded when context=desktop.
+# Includes window manager, applications, theming, and desktop session config.
+{
+  config,
+  pkgs,
+  ...
+}: {
+  imports = [
+    ./wm
+    ./apps
+    ./theme
+  ];
+
+  xdg = {
+    enable = true;
+    configFile."mimeapps.list".force = true;
+    mimeApps = {
+      enable = true;
+      associations.added = {
+        "application/zip" = ["org.gnome.FileRoller.desktop"];
+        "application/csv" = ["calc.desktop"];
+        "application/pdf" = ["okularApplication_pdf.desktop"];
+      };
+      defaultApplications = {
+        "application/zip" = ["org.gnome.FileRoller.desktop"];
+        "application/csv" = ["calc.desktop"];
+        "application/pdf" = ["okularApplication_pdf.desktop"];
+        "application/md" = ["nvim.desktop"];
+        "application/text" = ["nvim.desktop"];
+        "x-scheme-handler/http" = ["io.github.zen_browser.zen"];
+        "x-scheme-handler/https" = ["io.github.zen_browser.zen"];
+      };
+    };
+    userDirs = {
+      enable = true;
+      createDirectories = true;
+      setSessionVariables = true;
+    };
+  };
+
+  home.sessionVariables = {
+    WEBKIT_DISABLE_COMPOSITING_MODE = "1";
+    NIXOS_OZONE_WL = "1";
+    TERMINAL = "ghostty";
+    QT_QPA_PLATFORM = "wayland";
+    XDG_CURRENT_DESKTOP = "Hyprland";
+    XDG_SESSION_TYPE = "wayland";
+    XDG_SESSION_DESKTOP = "Hyprland";
+  };
+
+  home.sessionPath = [
+    "\${XDG_BIN_HOME}"
+    "\${HOME}/.cargo/bin"
+    "$HOME/.npm-global/bin"
+    "$HOME/.cache/.bun/bin"
+  ];
+
+  fonts.fontconfig.enable = true;
+
+  programs.ghostty = {
+    enable = true;
+    enableFishIntegration = true;
+    enableBashIntegration = true;
+    settings = {
+      font-family = "Fira Code";
+      copy-on-select = true;
+      foreground = "#${config.colorScheme.palette.base05}";
+      background = "#${config.colorScheme.palette.base00}";
+      selection-foreground = "#${config.colorScheme.palette.base07}";
+      selection-background = "#${config.colorScheme.palette.base02}";
+      cursor-color = "#${config.colorScheme.palette.base05}";
+      palette = [
+        "0=#${config.colorScheme.palette.base01}"
+        "1=#${config.colorScheme.palette.base08}"
+        "2=#${config.colorScheme.palette.base0B}"
+        "3=#${config.colorScheme.palette.base0A}"
+        "4=#${config.colorScheme.palette.base0D}"
+        "5=#${config.colorScheme.palette.base0E}"
+        "6=#${config.colorScheme.palette.base0C}"
+        "7=#${config.colorScheme.palette.base05}"
+        "8=#${config.colorScheme.palette.base03}"
+        "9=#${config.colorScheme.palette.base08}"
+        "10=#${config.colorScheme.palette.base0B}"
+        "11=#${config.colorScheme.palette.base0A}"
+        "12=#${config.colorScheme.palette.base0D}"
+        "13=#${config.colorScheme.palette.base0E}"
+        "14=#${config.colorScheme.palette.base0C}"
+        "15=#${config.colorScheme.palette.base07}"
+      ];
+    };
+  };
+
+  home.pointerCursor = {
+    gtk.enable = true;
+    package = pkgs.bibata-cursors;
+    name = "Bibata-Modern-Ice";
+    size = 20;
+  };
+
+  home.packages = with pkgs; [
+    appimage-run
+    bemoji
+    brave
+    distrobox
+    eigent
+    (element-desktop.override {
+      commandLineArgs = "--password-store=gnome-libsecret";
+    })
+    launch-webapp
+    file-roller
+    hyprpanel
+    seahorse
+    sushi
+    ksnip
+    msty-studio
+    nwg-look
+    rose-pine-hyprcursor
+    remmina
+    slack
+    telegram-desktop
+    vivaldi
+    vivaldi-ffmpeg-codecs
+    vibetyper
+  ];
+}