refactor: rename argument to avoid C++ keyword conflict

The parameter `template` in format_call_external_argv() was renamed
to `template_fmt` to avoid collision with the `template` keyword in
C++. This improves compatibility when the header is included in
C++ code.

src/common.c

@@ -660,17 +660,17 @@ call_external(gchar** argv)
  *
  * This function constructs an argument vector (argv) based on the provided template string, replacing placeholders ("%u" and "%p") with the provided URL and filename, respectively.
  *
- * @param template  The template string with placeholders.
- * @param url       The URL to replace "%u" (or NULL to skip).
- * @param filename  The filename to replace "%p" (or NULL to skip).
- * @return          The constructed argument vector (argv) as a null-terminated array of strings.
+ * @param template_fmt  The template string with placeholders.
+ * @param url           The URL to replace "%u" (or NULL to skip).
+ * @param filename      The filename to replace "%p" (or NULL to skip).
+ * @return              The constructed argument vector (argv) as a null-terminated array of strings.
  *
  * @note Remember to free the returned argument vector using `auto_gcharv` or `g_strfreev()`.
  */
 gchar**
-format_call_external_argv(const char* template, const char* url, const char* filename)
+format_call_external_argv(const char* template_fmt, const char* url, const char* filename)
 {
-    gchar** argv = g_strsplit(template, " ", 0);
+    gchar** argv = g_strsplit(template_fmt, " ", 0);
 
     guint num_args = 0;
     while (argv[num_args]) {
@@ -679,7 +679,7 @@ format_call_external_argv(const char* template, const char* url, const char* fil
             argv[num_args] = g_strdup(url);
         } else if (0 == g_strcmp0(argv[num_args], "%p") && filename != NULL) {
             g_free(argv[num_args]);
-            argv[num_args] = strdup(filename);
+            argv[num_args] = g_strdup(filename);
         }
         num_args++;
     }

src/common.h

@@ -198,7 +198,7 @@ void get_file_paths_recursive(const char* directory, GSList** contents);
 char* get_random_string(int length);
 
 gboolean call_external(gchar** argv);
-gchar** format_call_external_argv(const char* template, const char* url, const char* filename);
+gchar** format_call_external_argv(const char* template_fmt, const char* url, const char* filename);
 
 gchar* unique_filename_from_url(const char* url, const char* path);
 gchar* get_expanded_path(const char* path);