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/apps/crypto.nix

@@ -0,0 +1,16 @@
+# Cryptocurrency applications — Bisq, Monero GUI, and Trezor Suite.
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+with lib; let
+  cfg = config.desktop.apps.crypto;
+in {
+  options.desktop.apps.crypto.enable = mkEnableOption "enable crypto applications";
+
+  config = mkIf cfg.enable {
+    home.packages = with pkgs; [bisq2 monero-gui trezor-suite];
+  };
+}

home/desktop/apps/default.nix

@@ -0,0 +1,9 @@
+# Desktop apps aggregator — Obsidian, Office, web apps, and crypto tools.
+{...}: {
+  imports = [
+    ./obsidian.nix
+    ./office.nix
+    ./webapps.nix
+    ./crypto.nix
+  ];
+}

home/desktop/apps/obsidian.nix

@@ -0,0 +1,25 @@
+# Obsidian knowledge base with markdown MIME association.
+{
+  config,
+  lib,
+  ...
+}:
+with lib; let
+  cfg = config.desktop.apps.obsidian;
+in {
+  options.desktop.apps.obsidian.enable = mkEnableOption "enable Obsidian knowledge base";
+
+  config = mkIf cfg.enable {
+    programs.obsidian.enable = true;
+
+    xdg.mimeApps = {
+      enable = true;
+      associations.added = {
+        "text/markdown" = ["obsidian.desktop"];
+      };
+      defaultApplications = {
+        "text/markdown" = ["obsidian.desktop"];
+      };
+    };
+  };
+}

home/desktop/apps/office.nix

@@ -0,0 +1,16 @@
+# Office and productivity applications — LibreOffice and document tools.
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+with lib; let
+  cfg = config.desktop.apps.office;
+in {
+  options.desktop.apps.office.enable = mkEnableOption "install office and paperwork apps";
+
+  config = mkIf cfg.enable {
+    home.packages = [pkgs.libreoffice-fresh];
+  };
+}

home/desktop/apps/webapps.nix

@@ -0,0 +1,56 @@
+# Web application desktop entries — Teams, Outlook, Basecamp, and OpenCode launchers.
+{
+  pkgs,
+  lib,
+  ...
+}: let
+  icons = {
+    teams = pkgs.fetchurl {
+      url = "https://cdn.jsdelivr.net/gh/homarr-labs/dashboard-icons/svg/microsoft-teams.svg";
+      sha256 = "sha256-Pr9QS8nnXJq97r4/G3c6JXi34zxHl0ps9gcyI8cN/s8=";
+    };
+    outlook = pkgs.fetchurl {
+      url = "https://cdn.jsdelivr.net/gh/homarr-labs/dashboard-icons/svg/microsoft-outlook.svg";
+      sha256 = "sha256-3u8t5QNHFZvrAegxBiGicO4PjtMWhEaQSCv7MSSfLLc=";
+    };
+    opencode = pkgs.fetchurl {
+      url = "https://cdn.jsdelivr.net/gh/homarr-labs/dashboard-icons/svg/opencode-dark.svg";
+      sha256 = "1lms4f8habamvdh2qqqz9psx4py9wx23mmlkkds44pvrbq3bkj3n";
+    };
+  };
+in {
+  xdg.desktopEntries = {
+    teams = {
+      name = "Microsoft Teams";
+      exec = "launch-webapp https://teams.microsoft.com";
+      comment = "Open Microsoft Teams as a Desktop App";
+      categories = ["Application" "Network" "Chat"];
+      terminal = false;
+      icon = icons.teams;
+    };
+    outlook = {
+      name = "Microsoft Outlook";
+      exec = "launch-webapp https://outlook.office.com/mail/";
+      comment = "Open Microsoft Outlook as a Desktop App";
+      categories = ["Application" "Network"];
+      terminal = false;
+      icon = icons.outlook;
+    };
+    basecamp = {
+      name = "Basecamp";
+      exec = "launch-webapp https://3.basecamp.com/5996442/";
+      comment = "Open Basecamp as a Desktop App";
+      categories = ["Application" "Network"];
+      terminal = false;
+      icon = "/home/sascha.koenig/.local/share/icons/basecamp-logo.png";
+    };
+    opencode = {
+      name = "Opencode";
+      exec = "rofi-project-opener";
+      comment = "Open Opencode Terminal App";
+      categories = ["Application" "Development"];
+      terminal = false;
+      icon = icons.opencode;
+    };
+  };
+}