refactor: reorganize flake structure and consolidate user config

Directory structure:
- Move from src/ to root level (system/, user/)
- Remove unused machines (workstation, vm, laptop)

User configuration:
- Add user/home.nix for shared defaults (pass, essentials, default modules)
- Centralize user options in user/default.nix
- Move submodules to consistent paths (bash/bash, git/git, neovim/nvim, vim/vim)

Module reorganization:
- Flatten nested module structures (remove /modules/ subdirs)
- Split CLI vs GUI tools (dev/ for CLI, gui/dev/ for GUI)
- Move neovim/vim to top-level modules (not under utils/)
- Remove security.enable - pass now in user/home.nix
- Remove utils.enable - essentials now in user/home.nix
- Add security/yubikey module with yubikey-manager, age-plugin-yubikey
- Move pcb, design to gui/dev/
- Replace penpot docker wrapper with nixpkgs penpot-desktop
- Remove i3 config
- Remove deprecated wsl.nativeSystemd option

GUI improvements:
- Browser-focused mimeApps in gui/default.nix
- Each WM handles its own auto-start via profileExtra

Cleanup:
- Update README with new structure
- Update justfile paths and valid systems
- Fix submodule paths in .gitmodules

user/modules/gui/fun/config/discord.config.json

@@ -0,0 +1,82 @@
+{
+    "settings": {
+        "general": {
+            "menuBar": {
+                "hide": false
+            },
+            "tray": {
+                "disable": false
+            },
+            "taskbar": {
+                "flash": true
+            },
+            "window": {
+                "transparent": false,
+                "hideOnClose": false
+            }
+        },
+        "privacy": {
+            "blockApi": {
+                "science": true,
+                "typingIndicator": false,
+                "fingerprinting": true
+            },
+            "permissions": {
+                "video": null,
+                "audio": true,
+                "fullscreen": true,
+                "notifications": null,
+                "display-capture": true,
+                "background-sync": false
+            }
+        },
+        "advanced": {
+            "csp": {
+                "enabled": true
+            },
+            "cspThirdParty": {
+                "spotify": true,
+                "gif": true,
+                "hcaptcha": true,
+                "youtube": true,
+                "twitter": true,
+                "twitch": true,
+                "streamable": true,
+                "vimeo": true,
+                "soundcloud": true,
+                "paypal": true,
+                "audius": true,
+                "algolia": true,
+                "reddit": true,
+                "googleStorageApi": true
+            },
+            "currentInstance": {
+                "radio": 0
+            },
+            "devel": {
+                "enabled": true
+            },
+            "redirection": {
+                "warn": true
+            },
+            "optimize": {
+                "gpu": true
+            },
+            "webApi": {
+                "webGl": true
+            },
+            "unix": {
+                "autoscroll": false
+            }
+        }
+    },
+    "update": {
+        "notification": {
+            "version": "",
+            "till": ""
+        }
+    },
+    "screenShareStore": {
+        "audio": false
+    }
+}

user/modules/gui/fun/default.nix

@@ -0,0 +1,25 @@
+{ pkgs, lib, config, ... }:
+
+with lib;
+let
+  cfg = config.modules.user.gui.fun;
+
+in
+{ options.modules.user.gui.fun = { enable = mkEnableOption "Enable entertainment apps"; };
+  config = mkIf cfg.enable {
+    #programs.obs-studio = {
+    #  enable = true;
+    #  plugins = with pkgs.obs-studio-plugins; [
+    #    wlrobs
+    #    obs-pipewire-audio-capture
+    #    input-overlay
+    #  ];
+    #};
+
+    home.packages = with pkgs; [
+      ytmdesktop
+      discordo
+      webcord
+    ];
+  };
+}