feat: init serena onboarding & project memory files

Introduces the .serena directory with onboarding documentation, project architecture, code style, workflows, and related memory files for HugeGraph Toolchain.

These files provide guidelines and quick start information for new developers, covering project overview, design patterns, code conventions, testing, and development workflows.

Author: imbajin

.serena/.gitignore

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+/cache

.serena/memories/README_INDEX.md

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+# Memory Index - HugeGraph Toolchain Project
+
+## Onboarding Complete ✓
+
+This project has been successfully initialized with Serena MCP. Below is an index of all available memory files.
+
+## Available Memories (7 Core Files)
+
+### Core Project Information
+
+1. **project_overview.md** (125 lines)
+   - Project purpose and goals
+   - All 6 modules (client, loader, hubble, tools, client-go, spark-connector)
+   - Technology stack (Java 8, Node.js 18.20.8, Go, React, Spring Boot)
+   - Module dependencies and relationships
+   - External dependencies
+   - Project structure
+
+### Code Quality and Style
+
+2. **code_style_and_conventions.md** (311 lines)
+   - Java code style (indentation, naming, formatting)
+   - Naming conventions (classes, methods, variables)
+   - Import rules and prohibited imports
+   - Maven POM style
+   - Frontend code style (TypeScript, CSS/Less)
+   - Go code style
+   - Design patterns used in each module
+   - File organization standards
+   - Commit message format
+
+3. **task_completion_checklist.md** (372 lines) ⭐ **IMPORTANT**
+   - Code quality checks before committing
+   - Testing requirements
+   - Build verification steps
+   - Documentation update checklist
+   - Git pre-commit checklist
+   - Pull request checklist
+   - CI/CD pipeline details
+   - Common issues and solutions
+   - Release-specific tasks
+
+### Architecture and Design
+
+4. **architecture_and_design_patterns.md** (571 lines)
+   - Overall system architecture
+   - Module-specific architectures:
+     - hugegraph-client: Layered architecture, Manager pattern
+     - hugegraph-loader: Pipeline architecture
+     - hugegraph-hubble: Frontend (React+MobX) + Backend (Spring Boot)
+     - hugegraph-tools: Command pattern
+   - Design patterns (Factory, Builder, Strategy, Observer, Repository)
+   - Cross-cutting concerns (error handling, logging)
+   - Configuration management
+
+### Testing
+
+5. **testing_infrastructure.md** (634 lines)
+   - Testing philosophy (unit, integration, functional)
+   - Test organization and structure
+   - Module-specific testing:
+     - hugegraph-client: UnitTestSuite, ApiTestSuite, FuncTestSuite
+     - hugegraph-loader: Test profiles (unit, file, hdfs, jdbc, kafka)
+     - hugegraph-hubble: Backend (Spring Test) + Frontend (Jest)
+     - hugegraph-client-go: Go standard testing
+   - CI/CD testing pipelines
+   - Test coverage tools and targets
+   - Common testing patterns
+   - Debugging tests
+
+### Development Workflows
+
+6. **common_development_workflows.md** (657 lines)
+   - Daily development workflows:
+     - Starting new features
+     - Fixing bugs
+     - Adding tests
+     - Refactoring code
+   - Module-specific workflows
+   - Troubleshooting common issues
+   - Release workflow
+   - Useful development commands
+   - Git hooks setup
+   - IDE configuration (IntelliJ IDEA, VS Code)
+
+## Quick Start Guide
+
+### For New Developers
+
+1. **Read First**:
+   - `project_overview.md` - Understand what the project is
+   - `common_development_workflows.md` - Learn essential commands and workflows
+
+2. **Before Making Changes**:
+   - `code_style_and_conventions.md` - Learn coding standards
+   - `task_completion_checklist.md` - Know what to check before committing
+
+3. **When Working on Code**:
+   - `architecture_and_design_patterns.md` - Understand design patterns
+
+4. **When Writing Tests**:
+   - `testing_infrastructure.md` - Learn testing approach
+
+### For System Setup
+
+**Prerequisites** (macOS):
+```bash
+# Java 11 (required)
+/usr/libexec/java_home -V
+export JAVA_HOME=$(/usr/libexec/java_home -v 11)
+
+# Maven
+brew install maven
+
+# Node.js 18.20.8 (for Hubble)
+nvm install 18.20.8
+nvm use 18.20.8
+npm install -g yarn
+
+# Python 3 (for Hubble build)
+brew install python3
+pip3 install -r hugegraph-hubble/hubble-dist/assembly/travis/requirements.txt
+```
+
+**Build Entire Project**:
+```bash
+mvn clean install -DskipTests -Dmaven.javadoc.skip=true -ntp
+```
+
+**Run Tests**:
+```bash
+# Client tests
+cd hugegraph-client
+mvn test -Dtest=UnitTestSuite -ntp
+
+# Loader tests
+cd hugegraph-loader
+mvn test -P unit -ntp
+
+# Hubble tests
+cd hugegraph-hubble/hubble-fe
+yarn test
+```
+
+## Essential Commands Cheat Sheet
+
+### Build Commands
+```bash
+# Full project
+mvn clean install -DskipTests -Dmaven.javadoc.skip=true -ntp
+
+# Specific module (e.g., client)
+mvn install -pl hugegraph-client -am -DskipTests -ntp
+
+# Hubble (requires dependencies built first)
+mvn install -pl hugegraph-client,hugegraph-loader -am -DskipTests -ntp
+cd hugegraph-hubble
+mvn -e compile package -Dmaven.test.skip=true -ntp
+```
+
+### Testing Commands
+```bash
+# Client unit tests
+cd hugegraph-client && mvn test -Dtest=UnitTestSuite -ntp
+
+# Loader tests
+cd hugegraph-loader && mvn test -P unit -ntp
+
+# Single test
+mvn test -Dtest=ClassName#methodName -ntp
+```
+
+### Code Quality
+```bash
+# Checkstyle
+mvn checkstyle:check
+
+# License check
+mvn apache-rat:check
+
+# EditorConfig validation
+mvn editorconfig:check
+```
+
+### Git Commands (IMPORTANT: Always use --no-pager)
+```bash
+# View history
+git --no-pager log --oneline -10
+
+# View changes
+git --no-pager diff HEAD~1
+```
+
+**See `common_development_workflows.md` for complete command reference**
+
+## Key Project Facts
+
+- **Language**: Java 8 (main), Go, TypeScript
+- **Build Tool**: Maven 3.x
+- **Test Framework**: JUnit 4 + Mockito
+- **Frontend**: React + TypeScript + MobX (Node.js 18.20.8)
+- **Backend**: Spring Boot
+- **Version**: 1.7.0
+- **License**: Apache 2.0
+- **Repository**: https://github.com/apache/hugegraph-toolchain
+
+## Common Pitfalls to Avoid
+
+1. ❌ **DON'T** use `git log` without `--no-pager` flag
+2. ❌ **DON'T** commit without running checkstyle and tests
+3. ❌ **DON'T** use star imports (`import org.apache.*`)
+4. ❌ **DON'T** use `System.out.println` (use logger instead)
+5. ❌ **DON'T** forget Apache 2.0 license headers
+6. ❌ **DON'T** use tabs (use 4 spaces for Java, 2 for frontend)
+7. ❌ **DON'T** exceed 100 character line length
+8. ❌ **DON'T** commit code that fails CI checks
+
+## Getting Help
+
+- **Documentation**: https://hugegraph.apache.org/docs/
+- **Issues**: https://github.com/apache/hugegraph-toolchain/issues
+- **Mailing List**: dev@hugegraph.apache.org
+- **Memory Files**: Check `.serena/memories/` directory
+
+## Memory Statistics
+
+- **Total Memory Files**: 7 (including this index)
+- **Total Lines**: ~2,900+
+- **Total Size**: ~85KB
+- **Coverage Areas**: 
+  - Project overview and structure
+  - Code style and conventions
+  - Architecture and design patterns
+  - Testing infrastructure
+  - Development workflows
+  - Task completion checklists
+
+## Last Updated
+
+Onboarding completed: 2025-11-05
+
+---
+
+**Note**: All memories are stored in `.serena/memories/` directory and can be read using Serena MCP tools.