chore: initial commit

pi extension exposing a single search tool. Providers: Kagi (headless
Firefox against kagi.com session-token endpoint) and SearXNG (JSON API).
Config lives at ~/.pi/pi-search/config.json with env overrides.

flake.nix

@@ -0,0 +1,31 @@
+{
+  description = "pi-search extension development environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs =
+    { self
+    , nixpkgs
+    , flake-utils
+    ,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          packages = with pkgs; [
+            oxlint
+            nodejs_22
+            firefox
+            geckodriver
+          ];
+        };
+      }
+    );
+}