feat: add timezone support for schedule and user runtime (#282)

db/migrations/0001_init.up.sql

@@ -17,6 +17,7 @@ CREATE TABLE IF NOT EXISTS users (
   role user_role NOT NULL DEFAULT 'member',
   display_name TEXT,
   avatar_url TEXT,
+  timezone TEXT NOT NULL DEFAULT 'UTC',
   data_root TEXT,
   last_login_at TIMESTAMPTZ,
   is_active BOOLEAN NOT NULL DEFAULT true,
@@ -156,6 +157,7 @@ CREATE TABLE IF NOT EXISTS bots (
   type TEXT NOT NULL,
   display_name TEXT,
   avatar_url TEXT,
+  timezone TEXT,
   is_active BOOLEAN NOT NULL DEFAULT true,
   status TEXT NOT NULL DEFAULT 'ready',
   max_context_load_time INTEGER NOT NULL DEFAULT 1440,