[Feature] Add logging parameters and error output to terminal

[xyxinyang]

Motivation

💡 If this PR is a Cherry Pick, the PR title needs to follow the format by adding the [Cherry-Pick] label at the very beginning and appending the original PR ID at the end. For example, [Cherry-Pick][CI] Add check trigger and logic(#5191)

💡 如若此PR是Cherry Pick，PR标题需遵循格式，在最开始加上[Cherry-Pick]标签，以及最后面加上原PR ID，例如[Cherry-Pick][CI] Add check trigger and logic(#5191)

针对 FastDeploy 的日志系统进行优化，预计分 4 个 pr 完成。

pr	内容	状态
1	新增日志相关参数、错误同时输出到终端	当前 pr
2	日志通道划分、request.log 级别划分和聚合	待提交
3	worker_process.log、cache_manager.log、comm.log、paddle日志收敛和简化	待提交
4	trace.log 日志的规范化和整合	待提交

pr1 的错误输出是针对 work 的错误，其他错误输出终端需要在 pr2 划分通道中实现

Modifications

1. 新增日志相关环境变量

   • 新增 FD_LOG_LEVEL、FD_LOG_REQUESTS、FD_LOG_REQUESTS_LEVEL、FD_LOG_MAX_LEN、FD_TRACE 环境变量

2. 日志输出分流

   • 添加 MaxLevelFilter：INFO/DEBUG → stdout，ERROR/CRITICAL → stderr
   • 添加 console_stdout 和 console_stderr handlers

3. Worker 启动失败错误展示优化

   • 添加 _read_latest_worker_traceback()：读取 workerlog.* 中的 traceback
   • 添加 _format_worker_launch_failure_message()：格式化错误消息
   • 修改 _stop_profile()：返回 False 而非 raise RuntimeError，错误信息输出到终端

4. 其他

   • DailyRotatingFileHandler._open() 添加 mkdir 确保目录存在

Usage or Command

新增环境变量

变量名	说明	默认值
FD_LOG_LEVEL	全局日志级别，优先于 FD_DEBUG	INFO
FD_LOG_REQUESTS	请求日志总开关	1
FD_LOG_REQUESTS_LEVEL	请求日志详细级别 (0-3)	0
FD_LOG_MAX_LEN	请求日志字段截断最大长度	2048
FD_TRACE	统一 trace 开关：off/local/otel/all	off

当前环境变量未生效，会在后续 pr2 - pr4 用到，同时后续 pr 会删除旧的日志参数：FD_DEBUG 和 TRACES_ENABLE

Accuracy Tests

本次 pr 新增的环境变量未生效，在后续 pr2 - pr4 逐步用到。

worker 错误输出：

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
  • You can add new tags based on the PR content, but the semantics must be clear.
• Format your code, run pre-commit before commit.
• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

[paddle-bot]

Thanks for your contribution!

[codecov-commenter]

Codecov Report

❌ Patch coverage is 82.50000% with 7 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@dd2aa10). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
fastdeploy/engine/common_engine.py	79.16%	5 Missing ⚠️
fastdeploy/engine/engine.py	75.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #7098   +/-   ##
==========================================
  Coverage           ?   73.44%           
==========================================
  Files              ?      402           
  Lines              ?    56605           
  Branches           ?     8945           
==========================================
  Hits               ?    41573           
  Misses             ?    12090           
  Partials           ?     2942           

Flag	Coverage Δ
GPU	73.44% <82.50%> (?)

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