Add Apache license headers to source files (#77)

* Add Apache license headers to source files

* fix formatting

data/nodes.sql

@@ -1,4 +1,17 @@
--- nodes.sql
+-- Copyright (C) 2025 l5yth
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+
 PRAGMA journal_mode=WAL;
 
 CREATE TABLE IF NOT EXISTS nodes (