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>

packages/shared-types/src/index.ts

@@ -1422,13 +1422,17 @@ export interface PromptRuleStatusRequest {
 
 export interface ScheduleTask {
   id: number;
+  workspace_id: number | null;
   prompt_rule_id: number;
   prompt_rule_name: string | null;
   brand_id: number | null;
   brand_name: string | null;
   name: string;
   cron_expr: string;
-  target_platform: string | null;
+  auto_publish: boolean;
+  publish_account_ids: string[];
+  cover_asset_url: string | null;
+  cover_image_asset_id: number | null;
   enable_web_search: boolean;
   generate_count: number;
   start_at: string | null;
@@ -1444,7 +1448,10 @@ export interface ScheduleTaskRequest {
   brand_id?: number | null;
   name: string;
   cron_expr: string;
-  target_platform?: string;
+  auto_publish?: boolean;
+  publish_account_ids?: string[];
+  cover_asset_url?: string | null;
+  cover_image_asset_id?: number | null;
   enable_web_search?: boolean;
   generate_count?: number;
   start_at?: string;
@@ -1475,7 +1482,6 @@ export interface ScheduleTaskStatusRequest {
 export interface GenerateFromRuleRequest {
   prompt_rule_id: number;
   brand_id?: number;
-  target_platform?: string;
   extra_params?: Record<string, JsonValue>;
 }