Add NeuralNet private messaging MVP

src/main/resources/db/migration/V16__neuralnet.sql

@@ -0,0 +1,28 @@
+CREATE TABLE neuralnet_privacy (
+    username VARCHAR(100) PRIMARY KEY REFERENCES users(username) ON DELETE CASCADE ON UPDATE CASCADE,
+    enabled BOOLEAN NOT NULL DEFAULT FALSE
+);
+
+CREATE TABLE neuralnet_connections (
+    id BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+    requester VARCHAR(100) NOT NULL REFERENCES users(username) ON DELETE CASCADE ON UPDATE CASCADE,
+    addressee VARCHAR(100) NOT NULL REFERENCES users(username) ON DELETE CASCADE ON UPDATE CASCADE,
+    status VARCHAR(20) NOT NULL DEFAULT 'PENDING',
+    created_at TIMESTAMP NOT NULL,
+    responded_at TIMESTAMP,
+    CONSTRAINT uq_neuralnet_connection UNIQUE (requester, addressee),
+    CONSTRAINT chk_neuralnet_no_self CHECK (requester <> addressee)
+);
+CREATE INDEX idx_neuralnet_connection_addressee ON neuralnet_connections(addressee, status);
+
+CREATE TABLE neuralnet_messages (
+    id BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+    sender VARCHAR(100) NOT NULL REFERENCES users(username) ON DELETE CASCADE ON UPDATE CASCADE,
+    recipient VARCHAR(100) NOT NULL REFERENCES users(username) ON DELETE CASCADE ON UPDATE CASCADE,
+    body VARCHAR(2000) NOT NULL,
+    sent_at TIMESTAMP NOT NULL,
+    read_at TIMESTAMP,
+    reported BOOLEAN NOT NULL DEFAULT FALSE
+);
+CREATE INDEX idx_neuralnet_message_pair ON neuralnet_messages(sender, recipient, sent_at);
+CREATE INDEX idx_neuralnet_message_unread ON neuralnet_messages(recipient, read_at);