logger: contribute "light" theme overrides

Add logger-theme.{c,h} with the logger plugin contribution to the
built-in "light" theme: 2 entries (logger.color.backlog_end=darkgray,
logger.color.backlog_line=darkgray) tuned for a light-background
terminal.

Same 2D-array pattern as the other plugin contributions.

Default option values are NOT changed.

src/plugins/logger/CMakeLists.txt

@@ -27,6 +27,7 @@ add_library(logger MODULE
   logger-config.c logger-config.h
   logger-info.c logger-info.h
   logger-tail.c logger-tail.h
+  logger-theme.c logger-theme.h
 )
 set_target_properties(logger PROPERTIES PREFIX "")
 

src/plugins/logger/logger-theme.c

@@ -0,0 +1,70 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Sébastien Helleu <flashcode@flashtux.org>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * This file is part of WeeChat, the extensible chat client.
+ *
+ * WeeChat is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * WeeChat 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with WeeChat.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* logger contribution to built-in themes. */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stddef.h>
+
+#include "../weechat-plugin.h"
+#include "logger.h"
+#include "logger-theme.h"
+
+
+const char *logger_theme_light[][2] =
+{
+    { "logger.color.backlog_end",  "darkgray" },
+    { "logger.color.backlog_line", "darkgray" },
+    { NULL,                        NULL },
+};
+
+void
+logger_theme_register (const char *name, const char *entries[][2])
+{
+    struct t_hashtable *overrides;
+    int i;
+
+    if (!name || !entries)
+        return;
+
+    overrides = weechat_hashtable_new (32,
+                                       WEECHAT_HASHTABLE_STRING,
+                                       WEECHAT_HASHTABLE_STRING,
+                                       NULL, NULL);
+    if (!overrides)
+        return;
+
+    for (i = 0; entries[i][0]; i++)
+        weechat_hashtable_set (overrides, entries[i][0], entries[i][1]);
+
+    weechat_theme_register (name, overrides);
+
+    weechat_hashtable_free (overrides);
+}
+
+void
+logger_theme_init (void)
+{
+    logger_theme_register ("light", logger_theme_light);
+}

src/plugins/logger/logger-theme.h

@@ -0,0 +1,27 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Sébastien Helleu <flashcode@flashtux.org>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * This file is part of WeeChat, the extensible chat client.
+ *
+ * WeeChat is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * WeeChat 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with WeeChat.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WEECHAT_PLUGIN_LOGGER_THEME_H
+#define WEECHAT_PLUGIN_LOGGER_THEME_H
+
+extern void logger_theme_init (void);
+
+#endif /* WEECHAT_PLUGIN_LOGGER_THEME_H */

src/plugins/logger/logger.c

@@ -36,6 +36,7 @@
 #include "logger-command.h"
 #include "logger-config.h"
 #include "logger-info.h"
+#include "logger-theme.h"
 
 
 WEECHAT_PLUGIN_NAME(LOGGER_PLUGIN_NAME);
@@ -785,6 +786,8 @@ weechat_plugin_init (struct t_weechat_plugin *plugin, int argc, char *argv[])
 
     logger_config_read ();
 
+    logger_theme_init ();
+
     logger_command_init ();
 
     logger_buffer_start_all (1);