docs: update zellij-ps to reflect project switcher functionality

- Update package description and fix mainProgram typo
- Rewrite documentation to describe project switching, not process viewing
- Add PROJECT_FOLDERS configuration and usage examples
- Update all references across docs (README, guides, module overviews)

docs/modules/nixos/overview.md

@@ -0,0 +1,166 @@
+# NixOS Modules Overview
+
+Overview of available NixOS modules in m3ta-nixpkgs.
+
+## Available Modules
+
+- [ports](./ports.md) - Port management across hosts
+- [mem0](./mem0.md) - Mem0 REST API server
+
+## Importing Modules
+
+### Import All Modules
+
+```nix
+{config, ...}: {
+  imports = [
+    m3ta-nixpkgs.nixosModules.default
+  ];
+}
+```
+
+### Import Specific Module
+
+```nix
+{config, ...}: {
+  imports = [
+    m3ta-nixpkgs.nixosModules.ports
+    m3ta-nixpkgs.nixosModules.mem0
+  ];
+}
+```
+
+## Module Namespace
+
+All NixOS modules use the `m3ta.*` namespace:
+
+```nix
+# Port management
+m3ta.ports = {
+  enable = true;
+  definitions = {nginx = 80;};
+};
+
+# Mem0 service
+m3ta.mem0 = {
+  enable = true;
+  port = 8000;
+};
+```
+
+## Common Patterns
+
+### Enable Module
+
+All modules follow the pattern:
+
+```nix
+m3ta.moduleName = {
+  enable = true;
+  # ... options
+};
+```
+
+### Configuration
+
+Modules typically provide these sections:
+
+- `enable` - Enable/disable module
+- `package` - Custom package (optional)
+- Configuration options specific to module
+
+## Integration Examples
+
+### With Port Management
+
+```nix
+{config, ...}: {
+  imports = [
+    m3ta-nixpkgs.nixosModules.default
+  ];
+
+  m3ta.ports = {
+    enable = true;
+    definitions = {
+      nginx = 80;
+      grafana = 3000;
+      mem0 = 8000;
+    };
+    currentHost = config.networking.hostName;
+  };
+
+  m3ta.mem0 = {
+    enable = true;
+    port = config.m3ta.ports.get "mem0";
+  };
+
+  services.nginx = {
+    enable = true;
+    httpConfig = ''
+      server {
+        listen ${toString (config.m3ta.ports.get "nginx")};
+        root /var/www;
+      }
+    '';
+  };
+}
+```
+
+### With Home Manager
+
+```nix
+{config, ...}: {
+  # NixOS modules
+  imports = [
+    m3ta-nixpkgs.nixosModules.default
+  ];
+
+  # Home Manager integration
+  home-manager.users.myusername = {
+    imports = [
+      m3ta-nixpkgs.homeManagerModules.default
+    ];
+
+    m3ta.ports = {
+      enable = true;
+      definitions = {
+        dev-server = 3000;
+      };
+      currentHost = config.networking.hostName;
+    };
+  };
+}
+```
+
+## Module Locations
+
+- `modules/nixos/ports.nix` - Port management module
+- `modules/nixos/mem0.nix` - Mem0 REST API server module
+
+## Adding New Modules
+
+1. Create module file: `modules/nixos/my-module.nix`
+2. Follow standard pattern:
+
+```nix
+{ config, lib, pkgs, ... }:
+with lib; let
+  cfg = config.m3ta.myModule;
+in {
+  options.m3ta.myModule = {
+    enable = mkEnableOption "my module";
+  };
+
+  config = mkIf cfg.enable {
+    # Configuration
+  };
+}
+```
+
+3. Import in `modules/nixos/default.nix`
+
+## Related
+
+- [Port Management Guide](../guides/port-management.md) - Detailed port management usage
+- [Using Modules Guide](../guides/using-modules.md) - How to use modules
+- [Home Manager Modules](./home-manager/overview.md) - User-level modules