feat: add native Svelte UI for robot recording, teleop, and eval

Adds a generic web dashboard at ui/ that works with any robot/teleop
type in lerobot. Calls lerobot-record, lerobot-teleoperate, and
lerobot-eval as background subprocesses.

Features:
- Setup tab: robot type/port/id, dynamic camera configuration
- Record tab: dataset config, teleop device, start/stop recording
- Teleop tab: start/stop teleoperation
- Evaluate tab: policy path, env type, device config
- Live MJPEG camera preview (paused during subprocess, auto-restarts)
- Terminal-style log panel streaming subprocess stdout/stderr
- Hardware discovery: serial ports, CAN interfaces, OpenCV cameras
- Config persistence via localStorage
- Dark theme, responsive camera grid

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

ui/launch.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+# Launch LeRobot UI — backend (FastAPI) + frontend (Svelte/Vite)
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+# ---- Python dependencies ----
+if ! python -c "import fastapi" 2>/dev/null; then
+    echo "Installing Python dependencies..."
+    pip install -r requirements.txt
+fi
+
+# ---- Node dependencies ----
+if [ ! -d "node_modules" ]; then
+    echo "Installing Node dependencies..."
+    npm install
+fi
+
+# ---- Start backend ----
+echo "Starting backend server on :8000 ..."
+python server.py &
+BACKEND_PID=$!
+
+# Give the backend a moment to bind its port
+sleep 1
+
+# ---- Start frontend ----
+echo "Starting frontend dev server on :5173 ..."
+npm run dev &
+FRONTEND_PID=$!
+
+# ---- Cleanup on exit ----
+cleanup() {
+    echo ""
+    echo "Shutting down..."
+    kill "$BACKEND_PID"  2>/dev/null || true
+    kill "$FRONTEND_PID" 2>/dev/null || true
+}
+trap cleanup EXIT INT TERM
+
+echo ""
+echo "================================================"
+echo "  LeRobot UI   →  http://localhost:5173"
+echo "  Backend API  →  http://localhost:8000"
+echo "  Press Ctrl+C to stop"
+echo "================================================"
+echo ""
+
+wait