Initial commit: MCP server packages for Nix

- Add flake structure with overlay and packages exports
- Add manim-mcp-server as first packaged MCP server
- Add README.org with usage instructions and package templates
- Add packages/default.nix as package aggregator
- Add overlays/default.nix for nixpkgs integration

flake.nix

@@ -0,0 +1,67 @@
+{
+  nixConfig = {
+    extra-substituters = [
+      "https://nix-community.cachix.org"
+    ];
+    extra-trusted-public-keys = [
+      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+    ];
+  };
+
+  description = "MCP Server Packages for Nix";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    jailed-agents.url = "path:/conf/jailed-agents";
+  };
+
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+      jailed-agents,
+      ...
+    }:
+    {
+      # Overlay that adds all MCP packages to nixpkgs
+      overlays.default = import ./overlays/default.nix;
+    }
+    // flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ self.overlays.default ];
+        };
+
+        # Import all MCP packages
+        mcpPackages = import ./packages { inherit pkgs; };
+
+        # List of all MCP server packages (for devShell)
+        allMcpServers = builtins.attrValues mcpPackages ++ [ pkgs.mcp-nixos ];
+      in
+      {
+        # Export all packages
+        packages = mcpPackages // {
+          default = pkgs.symlinkJoin {
+            name = "mcp-servers";
+            paths = builtins.attrValues mcpPackages;
+          };
+        };
+
+        devShells.default = pkgs.mkShell {
+          packages =
+            allMcpServers
+            ++ [
+              pkgs.git
+              (jailed-agents.lib.${system}.makeJailed system {
+                agentTool = "opencode";
+                extraPkgs = allMcpServers;
+              })
+            ];
+        };
+      }
+    );
+}