add: some user api and all api desc

desc/sql/community/post_likes.sql

@@ -0,0 +1,14 @@
+CREATE TABLE post_likes (
+                            post_id BIGINT NOT NULL,
+                            user_id BIGINT NOT NULL,
+                            created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+
+    -- 复合主键，防止重复点赞
+                            PRIMARY KEY (post_id, user_id)
+);
+
+-- [核心索引] 优化 "feed流中判断我是否已赞" (user_id = ? AND post_id IN (...))
+CREATE INDEX idx_post_likes_lookup ON post_likes(user_id, post_id);
+
+-- [核心索引] 优化 "我赞过的帖子" 列表
+CREATE INDEX idx_post_likes_user_timeline ON post_likes(user_id, created_at DESC);