test(cli): use ..Default::default() in tests/os_routes.rs SplitRoutes literals

Companion to v3.5 — the new force_vpn_cidrs field broke the two integration
tests that used positional SplitRoutes literals instead of struct-update
syntax. Switched both to .. Default::default() so the test sites are
forward-compatible with any further SplitRoutes additions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/aura-cli/tests/os_routes.rs

@@ -17,9 +17,8 @@ fn dry_run_install_succeeds_on_any_platform() {
     let split = SplitRoutes {
         default: DefaultAction::Vpn,
         direct_cidrs: vec!["192.168.0.0/16".parse().unwrap()],
-        vpn_cidrs: Vec::new(),
         direct_hosts: vec!["1.2.3.4".parse().unwrap()],
-        vpn_hosts: Vec::new(),
+        ..Default::default()
     };
     let guard = OsRouteGuard::install("aura0", &split, None, None, true)
         .expect("dry_run install must succeed everywhere");
@@ -161,9 +160,8 @@ fn dry_run_install_windows_style_overrides_succeed_anywhere() {
     let split = SplitRoutes {
         default: DefaultAction::Vpn,
         direct_cidrs: vec!["192.168.0.0/16".parse().unwrap()],
-        vpn_cidrs: Vec::new(),
         direct_hosts: vec!["1.2.3.4".parse().unwrap()],
-        vpn_hosts: Vec::new(),
+        ..Default::default()
     };
     // On Windows the "egress" hint is the upstream interface IP, not its display name.
     // The dry-run path renders this verbatim into the windows plan.