feat(schedule-tasks): support auto-publish via media accounts

Replace the legacy target_platform string on schedule tasks with a
workspace-aware auto-publish payload (auto_publish + publish_account_ids
JSONB + cover_asset_url + cover_image_asset_id) and migrate the schema,
sqlc queries, generated models, domain struct, ScheduleTaskService DTOs,
and dispatch worker to round-trip the new fields. PromptRuleGeneration
gains a WithPublishJobService hook so executeGeneration can enqueue an
auto-publish job once the article is ready, and worker-generate wires
the publish-job service in. On the admin-web side, extract
PublishArticleModal's account-card builders into a shared
publish-account-cards module, rebuild GenerateTaskDrawer's schedule
mode around account selection plus a CoverPickerModal, and surface the
new "auto publish" column on ScheduleTaskTab. Shared types and i18n
strings cover the new fields.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/cmd/scheduler/main.go

@@ -60,7 +60,7 @@ func main() {
 		app.GenerationStreams,
 		generationCfg,
 		app.Config.LLM.MaxOutputTokens,
-	).WithCache(app.Cache)
+	).WithCache(app.Cache).WithLogger(app.Logger)
 
 	monitoringCallbackService := tenantapp.NewMonitoringCallbackService(
 		app.DB,

server/cmd/worker-generate/main.go

@@ -63,7 +63,15 @@ func main() {
 		app.GenerationStreams,
 		generationCfg,
 		app.Config.LLM.MaxOutputTokens,
+	).WithCache(app.Cache).WithLogger(app.Logger)
+
+	publishJobSvc := tenantapp.NewPublishJobService(
+		app.DB,
+		app.RabbitMQ,
+		app.Redis,
+		app.Logger,
 	).WithCache(app.Cache)
+	promptRuleSvc.WithPublishJobService(publishJobSvc)
 
 	imitationSvc := tenantapp.NewArticleImitationService(
 		app.DB,