Remove legacy vpn proxy code and simplify the client

test/server/entrypoint-tproxy.test.js

@@ -0,0 +1,15 @@
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+import test from 'node:test';
+
+const entrypoint = fs.readFileSync(
+  path.resolve(import.meta.dirname, '../../entrypoint.sh'),
+  'utf8',
+);
+
+test('gateway intercepts all public TCP and UDP traffic without source bypasses', () => {
+  assert.match(entrypoint, /-p tcp -j TPROXY --on-port "\$TPROXY_PORT"/);
+  assert.match(entrypoint, /-p udp -j TPROXY --on-port "\$TPROXY_PORT"/);
+  assert.doesNotMatch(entrypoint, /TPROXY_BYPASS_SOURCE_CIDRS|DIRECT_BYPASS_CACHE|ipset/);
+});