feat: add L4 (TCP/UDP) proxy host support via caddy-l4

- New l4_proxy_hosts table and Drizzle migration (0015)
- Full CRUD model layer with validation, audit logging, and Caddy config
  generation (buildL4Servers integrating into buildCaddyDocument)
- Server actions, paginated list page, create/edit/delete dialogs
- L4 port manager sidecar (docker/l4-port-manager) that auto-recreates
  the caddy container when port mappings change via a trigger file
- Auto-detects Docker Compose project name from caddy container labels
- Supports both named-volume and bind-mount (COMPOSE_HOST_DIR) deployments
- getL4PortsStatus simplified: status file is sole source of truth,
  trigger files deleted after processing to prevent stuck 'Waiting' banner
- Navigation entry added (CableIcon)
- Tests: unit (entrypoint.sh invariants + validation), integration (ports
  lifecycle + caddy config), E2E (CRUD + functional routing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/(dashboard)/DashboardLayoutClient.tsx

@@ -30,6 +30,7 @@ import SecurityIcon from "@mui/icons-material/Security";
 import SettingsIcon from "@mui/icons-material/Settings";
 import HistoryIcon from "@mui/icons-material/History";
 import GppBadIcon from "@mui/icons-material/GppBad";
+import CableIcon from "@mui/icons-material/Cable";
 import LogoutIcon from "@mui/icons-material/Logout";
 
 type User = {
@@ -42,6 +43,7 @@ type User = {
 const NAV_ITEMS = [
   { href: "/", label: "Overview", icon: DashboardIcon },
   { href: "/proxy-hosts", label: "Proxy Hosts", icon: SwapHorizIcon },
+  { href: "/l4-proxy-hosts", label: "L4 Proxy Hosts", icon: CableIcon },
   { href: "/access-lists", label: "Access Lists", icon: VpnKeyIcon },
   { href: "/certificates", label: "Certificates", icon: SecurityIcon },
   { href: "/waf", label: "WAF", icon: GppBadIcon },