chore: add secondary development guide in README.md

[junjiem]

Summary by CodeRabbit

Documentation

• New Secondary Development Guide: Added comprehensive documentation covering integration of DAT capabilities into Java applications, including Maven dependency configuration and quick start examples.
• Java Integration Examples: Provided practical code samples demonstrating initialization and streaming event handling for developers.
• Best Practices & Resources: Included recommended classes, additional examples, and implementation guidance for extending DAT functionality.

[coderabbitai]

Caution

Review failed

The pull request is closed.

Walkthrough

Pure documentation expansion—README.md enhanced with a comprehensive secondary development guide covering Maven dependencies, quick-start Java examples, DAT integration patterns in existing applications, and modular dependency configurations for dat-sdk components.

Changes

Cohort / File(s)

Summary

Secondary Development Guide Documentation README.md

Added complete "二次开发指南" (Secondary Development Guide) section with Maven dependency examples, Java quick-start code demonstrating ProjectRunner initialization and event streaming, recommended advanced classes (ProjectRunner, ProjectBuilder, ProjectSeeder), links to additional examples and best practices, modular dependency combinations for Embedding/Reranking/LLM/Database Adapter/DAT Agent components, and interface implementation guidance for dat-core.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

• Documentation additions only—no code logic, API changes, or runtime behavioral modifications
• Content is repetitive in structure and informational in nature (dependency declarations, code snippets, reference links)
• Straightforward verification of accuracy and completeness of Maven coordinates and code examples

Poem

📚✨ A rabbit hops through docs with glee,
New guides and snippets, clear for all to see,
Maven, Java, quick starts flow,
Dev gardens bloom—now watch them grow! 🌱

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch chore/update_readme

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📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 4387904 and 25e349d.

📒 Files selected for processing (1)

• README.md (1 hunks)

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}