feat(ECR-025): OpsCMS FeedSlot 只读并 Closed

栏目位目录（ops_feed_slots + /cms），复用 admin.cms.read。

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/migrations/000026_ops_feed_slots.down.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS ops_feed_slots;

apps/api/migrations/000026_ops_feed_slots.up.sql

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+-- ECR-025 OpsCMS FeedSlot (read catalog)
+CREATE TABLE IF NOT EXISTS ops_feed_slots (
+  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  code varchar(64) NOT NULL UNIQUE,
+  title varchar(128) NOT NULL,
+  slot_key varchar(64) NOT NULL,
+  placement varchar(32) NOT NULL
+    CHECK (placement IN ('home','explore','ask')),
+  active boolean NOT NULL DEFAULT true,
+  system boolean NOT NULL DEFAULT false,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  updated_at timestamptz NOT NULL DEFAULT now()
+);
+CREATE INDEX IF NOT EXISTS idx_ops_feed_slots_active ON ops_feed_slots(active);
+INSERT INTO ops_feed_slots(code, title, slot_key, placement, active, system)
+VALUES ('home_feed_main', '首页主信息流位', 'home.main', 'home', true, true)
+ON CONFLICT (code) DO NOTHING;