feat: add database config and migration system

server/db/migrations/001_initial.sql

@@ -0,0 +1,48 @@
+CREATE TABLE IF NOT EXISTS users (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  username TEXT UNIQUE NOT NULL,
+  password TEXT NOT NULL,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE TABLE IF NOT EXISTS records (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  user_id INTEGER NOT NULL,
+  type TEXT NOT NULL CHECK(type IN ('income', 'expense')),
+  amount REAL NOT NULL,
+  category TEXT NOT NULL,
+  date DATETIME NOT NULL,
+  note TEXT,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+CREATE TABLE IF NOT EXISTS recurring_bills (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  user_id INTEGER NOT NULL,
+  type TEXT NOT NULL CHECK(type IN ('income', 'expense')),
+  amount REAL NOT NULL,
+  category TEXT NOT NULL,
+  day INTEGER NOT NULL,
+  note TEXT,
+  is_active INTEGER DEFAULT 1,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+CREATE TABLE IF NOT EXISTS categories (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  user_id INTEGER NOT NULL,
+  type TEXT NOT NULL CHECK(type IN ('income', 'expense')),
+  name TEXT NOT NULL,
+  icon TEXT NOT NULL,
+  is_default INTEGER DEFAULT 0,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+CREATE TABLE IF NOT EXISTS migrations (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  name TEXT NOT NULL,
+  executed_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);