chore: 初始版本提交 - 简化架构 + 轮询改造

- 移除 Motia Streams 实时通信，改用 3 秒轮询
- 简化前端代码，移除冗余组件
- 简化后端架构，准备 FastAPI 重构
- 更新 pixi.toml 环境配置
- 保留 bttoxin_digger_v5_repro 作为参考文档

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

scripts/start_web.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+# Start both frontend and backend servers
+# Usage: ./scripts/start_web.sh [frontend_port] [backend_port]
+
+FRONTEND_PORT=${1:-5173}
+BACKEND_PORT=${2:-8000}
+
+echo "=========================================="
+echo "BtToxin Pipeline Web Services"
+echo "=========================================="
+echo "Frontend: http://localhost:${FRONTEND_PORT}"
+echo "Backend:  http://localhost:${BACKEND_PORT}"
+echo "=========================================="
+echo ""
+echo "Starting services..."
+
+# Create jobs directory if it doesn't exist
+mkdir -p jobs
+echo "Jobs directory: $(pwd)/jobs"
+
+# Start backend in background
+echo "[Backend] Starting FastAPI server on port ${BACKEND_PORT}..."
+uvicorn web.backend.main:app --reload --host 0.0.0.0 --port ${BACKEND_PORT} &
+BACKEND_PID=$!
+
+# Wait for backend to be ready
+sleep 2
+
+# Start frontend
+echo "[Frontend] Starting Vite dev server on port ${FRONTEND_PORT}..."
+cd frontend && pnpm dev --host --port ${FRONTEND_PORT} &
+FRONTEND_PID=$!
+
+echo ""
+echo "=========================================="
+echo "Services started:"
+echo "  - Backend (PID: ${BACKEND_PID}) on port ${BACKEND_PORT}"
+echo "  - Frontend (PID: ${FRONTEND_PID}) on port ${FRONTEND_PORT}"
+echo "=========================================="
+echo "Press Ctrl+C to stop all services"
+echo ""
+
+# Wait for any process to exit
+wait