Add MIT license with safety disclaimer

LICENSE

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+MIT License
+
+Copyright (c) 2025 ESP32 Bluetooth Relay Controller Contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+---
+
+## Safety Notice
+
+This software controls electrical relays that may be used with high-voltage AC power.
+The authors and contributors of this software are not responsible for:
+
+- Any injury, death, or property damage resulting from the use of this software
+- Improper wiring or installation of relay modules
+- Violations of local electrical codes
+- Use of components beyond their rated specifications
+
+Users are solely responsible for:
+- Following all applicable electrical codes and regulations
+- Ensuring proper installation by qualified electricians when required
+- Using appropriate safety equipment and practices
+- Testing systems thoroughly before deployment
+- Implementing proper circuit protection (fuses, breakers, etc.)
+
+**ALWAYS exercise extreme caution when working with electricity, especially AC mains voltage.**