legal: add AGPL-3.0 license, copyright headers, commercial license info

- LICENSE: GNU AGPL-3.0 (full text)
- Copyright headers added to all 15 source files in src/
- COMMERCIAL_LICENSE.md: dual-license explanation (AGPL + commercial)

src/parser_telemetry_tool.rs

@@ -1,3 +1,18 @@
+// rusty-telemetry — Sim racing telemetry analysis platform
+// Copyright (C) 2026  Jan-Peter v. Hunnius
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero 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 Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
 //! Binary parser for Telemetry Tool plugin packets (port 10101).
 //!
 //! The Telemetry Tool is a third-party AC Python plugin by IkoRein v1.3.