chore: add copyright headers to all source files

internal/config/config.go

@@ -1,3 +1,6 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
 //go:build linux || freebsd
 
 // Package config loads nuntius configuration from a TOML file.

internal/config/config_test.go

@@ -1,3 +1,6 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
 //go:build linux || freebsd
 
 package config

internal/email/sender.go

@@ -1,3 +1,6 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
 //go:build linux || freebsd
 
 // Package email handles SMTP message composition and delivery.

internal/handler/contact.go

@@ -1,3 +1,6 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
 //go:build linux || freebsd
 
 package handler

internal/storage/newsletter.go

@@ -1,3 +1,6 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
 //go:build linux || freebsd
 
 // Package storage provides file-based persistence for nuntius.

internal/storage/newsletter_test.go

@@ -1,3 +1,6 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
 //go:build linux || freebsd
 
 package storage

internal/version/version.go

@@ -1,3 +1,6 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
 //go:build linux || freebsd
 
 // Package version exposes the nuntius release identity.