feat: wire discuss button in briefing RSS cards, cap cards at 3

Adds discussArticle() to BriefingApi and wires it through to the
RSS news cards in BriefingScreen so tapping Discuss opens a chat
conversation seeded with the article. Also caps RSS cards per
message at 3 to avoid overly long briefing threads.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

linux/flutter/generated_plugin_registrant.cc

@@ -8,6 +8,7 @@
 
 #include <flutter_timezone/flutter_timezone_plugin.h>
 #include <open_file_linux/open_file_linux_plugin.h>
+#include <record_linux/record_linux_plugin.h>
 #include <url_launcher_linux/url_launcher_plugin.h>
 
 void fl_register_plugins(FlPluginRegistry* registry) {
@@ -17,6 +18,9 @@ void fl_register_plugins(FlPluginRegistry* registry) {
   g_autoptr(FlPluginRegistrar) open_file_linux_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "OpenFileLinuxPlugin");
   open_file_linux_plugin_register_with_registrar(open_file_linux_registrar);
+  g_autoptr(FlPluginRegistrar) record_linux_registrar =
+      fl_plugin_registry_get_registrar_for_plugin(registry, "RecordLinuxPlugin");
+  record_linux_plugin_register_with_registrar(record_linux_registrar);
   g_autoptr(FlPluginRegistrar) url_launcher_linux_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "UrlLauncherPlugin");
   url_launcher_plugin_register_with_registrar(url_launcher_linux_registrar);

linux/flutter/generated_plugins.cmake

@@ -5,6 +5,7 @@
 list(APPEND FLUTTER_PLUGIN_LIST
   flutter_timezone
   open_file_linux
+  record_linux
   url_launcher_linux
 )