Update .gitignore and add flake.nix patching script for Flutter version management

flake.nix

@@ -4,6 +4,7 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    nixpkgs-flutter.url = "github:NixOS/nixpkgs/b9c03fbbaf84d85bb28eee530c7e9edc4021ca1b";
   };
 
   outputs =
@@ -11,16 +12,23 @@
       self,
       nixpkgs,
       flake-utils,
+      nixpkgs-flutter,
     }:
     flake-utils.lib.eachDefaultSystem (
       system:
       let
+
         pkgs = import nixpkgs {
           inherit system;
           config = {
             allowUnfree = true;
             android_sdk.accept_license = true;
           };
+          overlays = [
+            (final: prev: {
+              flutter-pkg = import (self.inputs.nixpkgs-flutter) { inherit system; };
+            })
+          ];
         };
 
         androidSdk =
@@ -69,7 +77,7 @@
             with pkgs;
             [
               # Mobile development
-              flutter
+              pkgs.flutter-pkg.flutter
               fvm-wrapper
               jdk17
 
@@ -80,6 +88,7 @@
               # Python & task runner
               python3
               python3Packages.invoke
+              jq
 
               # System dependencies for Flutter on Linux
               git