add note replies model

src-tauri/migrations/20230619082415_add_replies.sql

@@ -0,0 +1,13 @@
+-- Add migration script here
+CREATE TABLE
+  replies (
+    id INTEGER NOT NULL PRIMARY KEY,
+    parent_id TEXT NOT NULL,
+    event_id TEXT NOT NULL UNIQUE,
+    pubkey TEXT NOT NULL,
+    kind INTEGER NOT NULL DEFAULT 1,
+    tags JSON,
+    content TEXT NOT NULL,
+    created_at INTEGER NOT NULL,
+    FOREIGN KEY (parent_id) REFERENCES notes (event_id)
+  );