feat(social): add friends, private chats, inbox and music sharing

services/api/migrations/00019_social.sql

@@ -0,0 +1,52 @@
+-- +goose Up
+CREATE TABLE friendships (
+  low_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  high_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  sender_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  accepted boolean NOT NULL DEFAULT false,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY(low_id,high_id),
+  CHECK(low_id < high_id),
+  CHECK(sender_id IN (low_id,high_id))
+);
+CREATE INDEX friendships_high_idx ON friendships(high_id);
+CREATE TABLE social_blocks (
+  user_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  peer_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  PRIMARY KEY(user_id,peer_id), CHECK(user_id <> peer_id)
+);
+CREATE TABLE direct_messages (
+  seq bigserial PRIMARY KEY,
+  id uuid NOT NULL UNIQUE,
+  sender_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  recipient_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  text text NOT NULL DEFAULT '',
+  attachment_kind text NOT NULL DEFAULT 'none' CHECK(attachment_kind IN ('none','track','playlist')),
+  attachment_id uuid,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  read_at timestamptz,
+  CHECK(sender_id <> recipient_id),
+  CHECK(length(text) <= 4000),
+  CHECK((attachment_kind='none' AND attachment_id IS NULL AND length(trim(text))>0)
+     OR (attachment_kind<>'none' AND attachment_id IS NOT NULL))
+);
+CREATE INDEX direct_messages_pair_idx ON direct_messages(LEAST(sender_id,recipient_id),GREATEST(sender_id,recipient_id),seq DESC);
+CREATE INDEX direct_messages_unread_idx ON direct_messages(recipient_id,sender_id,seq) WHERE read_at IS NULL;
+CREATE INDEX direct_messages_sender_time_idx ON direct_messages(sender_id,created_at DESC);
+CREATE TABLE social_notifications (
+  id uuid PRIMARY KEY,
+  user_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  actor_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  kind text NOT NULL CHECK(kind IN ('friend_request','friend_accepted','message','music')),
+  message_seq bigint REFERENCES direct_messages(seq) ON DELETE CASCADE,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  read_at timestamptz
+);
+CREATE INDEX social_notifications_user_idx ON social_notifications(user_id,created_at DESC);
+CREATE INDEX social_notifications_request_rate_idx ON social_notifications(actor_id,created_at DESC) WHERE kind='friend_request';
+
+-- +goose Down
+DROP TABLE social_notifications;
+DROP TABLE direct_messages;
+DROP TABLE social_blocks;
+DROP TABLE friendships;