feat: project structure and nix build setup

- Add CLI entry point with urfave/cli/v2 (serve, index, list, search commands)
- Add database interface and implementations for PostgreSQL and SQLite
- Add schema versioning with automatic recreation on version mismatch
- Add MCP protocol types and server scaffold
- Add NixOS option types
- Configure flake.nix with devShell and buildGoModule package

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.nix

@@ -1,15 +1,64 @@
 {
-  description = "A very basic flake";
+  description = "LabMCP - Collection of MCP servers";
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
   };
 
-  outputs = { self, nixpkgs }: {
+  outputs = { self, nixpkgs }:
+    let
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+      pkgsFor = system: nixpkgs.legacyPackages.${system};
+    in
+    {
+      packages = forAllSystems (system:
+        let
+          pkgs = pkgsFor system;
+        in
+        {
+          nixos-options = pkgs.buildGoModule {
+            pname = "nixos-options-mcp";
+            version = "0.1.0";
+            src = ./.;
 
-    packages.x86_64-linux.hello = nixpkgs.legacyPackages.x86_64-linux.hello;
+            vendorHash = null; # Will be set after first build
 
-    packages.x86_64-linux.default = self.packages.x86_64-linux.hello;
+            subPackages = [ "cmd/nixos-options" ];
 
-  };
+            meta = with pkgs.lib; {
+              description = "MCP server for NixOS options search and query";
+              homepage = "https://git.t-juice.club/torjus/labmcp";
+              license = licenses.mit;
+              maintainers = [ ];
+              mainProgram = "nixos-options";
+            };
+          };
+
+          default = self.packages.${system}.nixos-options;
+        });
+
+      devShells = forAllSystems (system:
+        let
+          pkgs = pkgsFor system;
+        in
+        {
+          default = pkgs.mkShell {
+            buildInputs = with pkgs; [
+              go_1_24
+              gopls
+              gotools
+              go-tools
+              golangci-lint
+              postgresql
+              sqlite
+            ];
+
+            shellHook = ''
+              echo "LabMCP development shell"
+              echo "Go version: $(go version)"
+            '';
+          };
+        });
+    };
 }