Use internal logger package, add go.mod, build script and docs

[gwind]

Motivation

• Remove the external github.com/sirupsen/logrus dependency by providing a lightweight internal logger that matches the existing call sites.
• Introduce module metadata and developer-facing build/docs to simplify local development and multi-platform builds.

Description

• Replaced imports of github.com/sirupsen/logrus with an internal alias logrus "github.com/ooclab/es/logger" across examples, tests, link, session, tunnel and proto packages.
• Added a new logger package implementing the minimal logging API used by the codebase including SetLevel, Debug/Debugf, Infof, Warn/Warnf, Error/Errorf, Fatalln, and WithField/WithFields with an Entry type.
• Added go.mod with module github.com/ooclab/es and go 1.25.0 to enable module mode.
• Added scripts/build_multi_platform.sh to build for multiple OS/ARCH targets and a Chinese-language developer guide docs/zh_CN/Go环境与多平台编译指南.md.

Testing

• Ran unit tests with go test ./... which completed successfully.
• Built all packages locally across targets with ./scripts/build_multi_platform.sh which completed without errors.
• Static checks (basic build) were validated by running go build ./... and succeeded.

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Codex Task