chore: add license headers to source files

build.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (C) 2026, Nathan Gill
+
 use time::{OffsetDateTime, format_description::well_known::Iso8601};
 
 /// build helper for generating version strings from environment

src/auth_sys.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (C) 2026, Nathan Gill
+
 #[cfg(not(target_os = "openbsd"))]
 mod pam_backend {
     use std::{

src/comm.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (C) 2026, Nathan Gill
+
 use std::{
     marker::PhantomData,
     os::fd::{AsFd, OwnedFd},

src/event_loop.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (C) 2026, Nathan Gill
+
 use std::{
     os::fd::RawFd,
     time::{Duration, Instant},

src/font.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (C) 2026, Nathan Gill
+
 pub trait FontInfo {
     fn font_height(&self) -> f64;
 }