feat: add admin apis

migrations/0040_soft_delete.up.sql

@@ -0,0 +1,18 @@
+-- Soft-delete (admin moderation) for posts and comments. Additive: the column
+-- is nullable and defaults to NULL, and every read query now filters
+-- `deleted_at IS NULL` — a no-op for existing rows (all NULL), so nothing in
+-- the live app changes until an admin actually deletes something. A soft-
+-- deleted row disappears from all reads but stays in the table, recoverable
+-- via the admin "restore" action.
+ALTER TABLE posts
+    ADD COLUMN IF NOT EXISTS deleted_at TIMESTAMPTZ;
+
+ALTER TABLE post_comments
+    ADD COLUMN IF NOT EXISTS deleted_at TIMESTAMPTZ;
+
+-- Partial indexes keep the hot "not deleted" reads fast (they match the
+-- deleted_at IS NULL predicate now on every posts/comments query).
+CREATE INDEX IF NOT EXISTS posts_not_deleted_idx
+    ON posts (created_at DESC) WHERE deleted_at IS NULL;
+CREATE INDEX IF NOT EXISTS post_comments_not_deleted_idx
+    ON post_comments (post_id) WHERE deleted_at IS NULL;