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>

apps/admin-web/src/i18n/messages/en-US.ts

@@ -1254,10 +1254,20 @@ const enUS = {
       platformUnauthorized: "Unauthorized",
       platformEmptyTitle: "No publish platforms",
       platformEmptyHint: "No platform data is available yet. Please verify the Media Management setup first.",
+      publishSection: "Publish Settings",
+      autoPublish: "Auto publish",
+      autoPublishHint: "When enabled, scheduled articles enter the publish queue after generation.",
+      publishAccounts: "Media accounts",
+      publishAccountsHint: "Choose specific accounts. Offline clients queue first and continue after reconnecting.",
+      publishAccountEmptyTitle: "No media accounts",
+      publishAccountEmptyHint: "Bind media accounts in the desktop client before configuring auto publish.",
       cover: "Cover image",
       coverHint: "Keep the cover clear, complete, and visually polished.",
+      scheduleCoverHint: "Cover is off by default. Enable it to save a cover to generated articles for publishing.",
+      scheduleCoverRequiredHint: "A selected account platform requires a cover image before publishing.",
       coverUpload: "Upload cover image",
       coverUploadHint: "Local preview only for now",
+      scheduleCoverUploadHint: "Choose from local files or the asset library",
       scheduleTime: "Schedule article generation",
       scheduleEveryDay: "Every day",
       enableWebSearch: "Enable web search for generation",
@@ -1276,7 +1286,9 @@ const enUS = {
       name: "Task name",
       rule: "Prompt rule",
       cron: "Frequency",
-      platform: "Target platform",
+      autoPublish: "Auto publish",
+      manualPublish: "Manual publish",
+      autoPublishAccountCount: "Auto · {count} accounts",
       nextRun: "Next run",
       startAt: "Start time",
       endAt: "End time",
@@ -1341,6 +1353,8 @@ const enUS = {
       missingPromptRule: "Choose a prompt first.",
       invalidGenerateCount: "Article count must be at least 1.",
       invalidScheduleTime: "Choose a valid schedule time.",
+      missingPublishAccounts: "Choose at least one media account when auto publish is enabled.",
+      missingScheduleCover: "A selected media account platform requires a cover image.",
       missingPromptName: "Enter a prompt name first.",
       missingPromptContent: "Enter prompt content first.",
     },