chore: GPL-3.0 license propagated into *.go files in backend

.envlicense

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+# Define the license header
+LICENSE_HEADER='// Copyright (c) 2025 Nikolai Papin
+// 
+// This file is part of Easywish
+// 
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+// the GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+'
+
+# Loop through all .go files recursively
+find . -name '*.go' | while read -r file; do
+    # Check if the file exists
+    if [[ -f "$file" ]]; then
+        # Prepend the license header to the file
+        echo -e "$LICENSE_HEADER\n$(cat "$file")" > "$file"
+        echo "Updated $file"
+    fi
+done
+