接入 OTel 链路追踪 + 镜像默认启用

抓取-解析链路原本只有日志，出现"抓回内容但解析不出预期字段"时定位慢。
接入 OpenTelemetry traces（FastAPI/httpx 自动 + 手写 fetch/parse span），
解析失败时把页面 HTML 作为 span event 上报，便于事后复现。
Dockerfile 默认开启，镜像一启动即导出到自建 OTLP endpoint。

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

pyproject.toml

@@ -7,6 +7,11 @@ dependencies = [
     "fastapi>=0.115.0,<1.0.0",
     "httpx[http2]>=0.27.0,<1.0.0",
     "loguru>=0.7.0,<1.0.0",
+    "opentelemetry-api>=1.27.0,<2.0.0",
+    "opentelemetry-exporter-otlp>=1.27.0,<2.0.0",
+    "opentelemetry-instrumentation-fastapi>=0.48b0,<1.0.0",
+    "opentelemetry-instrumentation-httpx>=0.48b0,<1.0.0",
+    "opentelemetry-sdk>=1.27.0,<2.0.0",
     "pydantic>=2.0.0,<3.0.0",
     "pydantic-settings>=2.4.0,<3.0.0",
     "selectolax>=0.3.21,<1.0.0",