Add saved port forwarding rules and mode switch

migrations/0004_forward_rules.sql

@@ -0,0 +1,8 @@
+CREATE TABLE IF NOT EXISTS forward_rules (
+  id TEXT PRIMARY KEY,
+  account_id TEXT NOT NULL,
+  encrypted_payload TEXT NOT NULL,
+  updated_at INTEGER NOT NULL
+);
+
+CREATE INDEX IF NOT EXISTS forward_rules_account_updated ON forward_rules(account_id, updated_at DESC);