perf: sync protocol and core hardening updates

deploy/migrations/0079_login_code_message_deliveries.up.sql

@@ -0,0 +1,22 @@
+-- A phone_code_hash identifies exactly one account-visible 777000 login-code
+-- notification. Store only its SHA-256 digest plus compact immutable allocation
+-- facts; the secret code body remains solely in private_messages/message_boxes.
+CREATE TABLE login_code_message_deliveries (
+    delivery_key bytea PRIMARY KEY,
+    code_fingerprint bytea NOT NULL,
+    user_id bigint NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    private_message_id bigint NOT NULL CHECK (private_message_id > 0),
+    message_box_id integer NOT NULL CHECK (message_box_id > 0),
+    pts integer NOT NULL CHECK (pts > 0),
+    message_date integer NOT NULL CHECK (message_date > 0),
+    created_at timestamptz NOT NULL DEFAULT now(),
+    CONSTRAINT login_code_message_deliveries_key_size CHECK (octet_length(delivery_key) = 32),
+    CONSTRAINT login_code_message_deliveries_fingerprint_size CHECK (octet_length(code_fingerprint) = 32),
+    CONSTRAINT login_code_message_deliveries_user_box_unique UNIQUE (user_id, message_box_id),
+    CONSTRAINT login_code_message_deliveries_user_pts_unique UNIQUE (user_id, pts)
+);
+
+COMMENT ON COLUMN login_code_message_deliveries.delivery_key IS
+    'SHA-256(phone_code_hash); raw phone_code_hash is never persisted';
+COMMENT ON COLUMN login_code_message_deliveries.code_fingerprint IS
+    'HMAC-SHA-256(code), keyed by the non-persisted raw phone_code_hash';