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>

pixi.toml

@@ -54,12 +54,10 @@ frontend = ["frontend"]
 webbackend = ["webbackend"]
 
 # =========================
-# pixi tasks
+# pipeline tasks
 # =========================
 [feature.pipeline.tasks]
-# 完整 pipeline（三阶段）
 pipeline = "python scripts/run_single_fna_pipeline.py"
-# 单独阶段
 digger-only = "python scripts/run_digger_stage.py"
 shotter = "python scripts/bttoxin_shoter.py"
 plot = "python scripts/plot_shotter.py"
@@ -69,7 +67,7 @@ plot = "python scripts/plot_shotter.py"
 # =========================
 [feature.frontend.tasks]
 fe-install = { cmd = "pnpm install", cwd = "frontend" }
-fe-dev = { cmd = "pnpm dev", cwd = "frontend" }
+fe-dev = { cmd = "pnpm dev --host", cwd = "frontend" }
 fe-build = { cmd = "pnpm build", cwd = "frontend" }
 fe-test = { cmd = "pnpm test:unit --run", cwd = "frontend" }
 fe-lint = { cmd = "pnpm lint", cwd = "frontend" }
@@ -80,3 +78,4 @@ fe-lint = { cmd = "pnpm lint", cwd = "frontend" }
 [feature.webbackend.tasks]
 api-dev = "uvicorn web.backend.main:app --reload --host 0.0.0.0 --port 8000"
 api-test = "pytest web/backend/ -v"
+web-start = "bash scripts/start_web.sh"