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/20260401103000_create_template_assist_tasks.up.sql

@@ -0,0 +1,19 @@
+CREATE TABLE template_assist_tasks (
+    id            VARCHAR(64) PRIMARY KEY,
+    tenant_id     BIGINT NOT NULL REFERENCES tenants(id),
+    template_id   BIGINT NOT NULL REFERENCES article_templates(id),
+    status        VARCHAR(20) NOT NULL DEFAULT 'queued',
+    request_json  JSONB NOT NULL DEFAULT '{}'::jsonb,
+    result_json   JSONB,
+    error_message TEXT,
+    started_at    TIMESTAMPTZ,
+    completed_at  TIMESTAMPTZ,
+    created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at    TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX idx_template_assist_tasks_tenant_created
+    ON template_assist_tasks(tenant_id, created_at DESC);
+
+CREATE INDEX idx_template_assist_tasks_status_created
+    ON template_assist_tasks(status, created_at DESC);