feat(migrations): Harden task audit tracking and optimize article templates

- Added migration to harden task audit tracking by modifying audit_logs and related tables.
- Introduced operator_id to several tables for better tracking of actions.
- Updated article_templates with new prompt templates for various article types, enhancing content generation.
- Created prompt_rules and schedule_tasks tables to manage content generation rules and scheduling.
- Added foreign key constraints to articles for better data integrity.

server/migrations/20260401180001_create_schedule_tasks.up.sql

@@ -0,0 +1,18 @@
+CREATE TABLE schedule_tasks (
+    id              BIGSERIAL PRIMARY KEY,
+    tenant_id       BIGINT NOT NULL REFERENCES tenants(id),
+    prompt_rule_id  BIGINT NOT NULL REFERENCES prompt_rules(id),
+    brand_id        BIGINT REFERENCES brands(id),
+    name            VARCHAR(100) NOT NULL,
+    cron_expr       VARCHAR(100) NOT NULL,
+    target_platform VARCHAR(50),
+    start_at        TIMESTAMPTZ,
+    end_at          TIMESTAMPTZ,
+    next_run_at     TIMESTAMPTZ,
+    status          VARCHAR(20) NOT NULL DEFAULT 'enabled',
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    deleted_at      TIMESTAMPTZ
+);
+CREATE INDEX idx_schedule_task_tenant ON schedule_tasks(tenant_id, created_at DESC);
+CREATE INDEX idx_schedule_task_next_run ON schedule_tasks(status, next_run_at) WHERE deleted_at IS NULL;