[docs] Add CLAUDE.md for Claude Code guidance

Add CLAUDE.md file with build commands, architecture overview, and key technologies for future Claude Code instances.

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build Commands
+
+### Backend (Java/Maven)
+
+```bash
+# Clean build (skip tests)
+mvn clean package -DskipTests -Dspotless.skip=true
+
+# Run all tests
+mvn test
+
+# Run single test class
+mvn test -Dtest=ClassName
+
+# Full CI build
+mvn -B package --file pom.xml
+```
+
+**Requirements:** Java 21, Maven
+
+### Frontend (pnpm/React)
+
+```bash
+cd webapp
+
+# Install dependencies
+pnpm install
+
+# Start dev server (port 9000)
+pnpm dev
+
+# Production build
+pnpm build
+
+# Run tests
+pnpm test
+```
+
+**Requirements:** Node.js >=16, pnpm 9.12.3+
+
+### Quick Start
+
+```bash
+# Build full release
+./assembly/bin/supersonic-build.sh standalone
+
+# Start service
+./assembly/bin/supersonic-daemon.sh start
+
+# Stop service
+./assembly/bin/supersonic-daemon.sh stop
+```
+
+Visit http://localhost:9080 after startup.
+
+## Architecture Overview
+
+SuperSonic unifies **Chat BI** (LLM-powered) and **Headless BI** (semantic layer) paradigms.
+
+### Core Modules
+
+```
+supersonic/
+├── auth/           # Authentication & authorization (SPI-based)
+├── chat/           # Chat BI module - LLM-powered Q&A interface
+├── common/         # Shared utilities
+├── headless/       # Headless BI - semantic layer with open API
+├── launchers/      # Application entry points
+│   ├── standalone/ # Combined Chat + Headless (default)
+│   ├── chat/       # Chat-only service
+│   └── headless/   # Headless-only service
+└── webapp/         # Frontend React app (UmiJS 4 + Ant Design)
+```
+
+### Data Flow
+
+1. **Knowledge Base**: Extracts schema from semantic models, builds dictionary/index for schema mapping
+2. **Schema Mapper**: Identifies metrics/dimensions/entities/values in user queries
+3. **Semantic Parser**: Generates S2SQL (semantic SQL) using rule-based and LLM-based parsers
+4. **Semantic Corrector**: Validates and corrects semantic queries
+5. **Semantic Translator**: Converts S2SQL to executable SQL
+
+### Key Entry Points
+
+- `StandaloneLauncher.java` - Combined service with `scanBasePackages: ["com.tencent.supersonic", "dev.langchain4j"]`
+- `ChatLauncher.java` - Chat BI only
+- `HeadlessLauncher.java` - Headless BI only
+
+## Key Technologies
+
+**Backend:** Spring Boot 3.3.9, MyBatis-Plus 3.5.10.1, LangChain4j 0.36.2, JSqlParser 4.9, Calcite 1.38.0
+
+**Frontend:** React 18, UmiJS 4, Ant Design 5.17.4, ECharts 5.0.2, AntV G6/X6
+
+**Databases:** MySQL, PostgreSQL (with pgvector), H2, ClickHouse, StarRocks, Presto, Trino, DuckDB
+
+## Testing
+
+**Java tests:** JUnit 5, Mockito. Located in `src/test/java/` of each module.
+
+**Frontend tests:** Jest with Puppeteer environment in `webapp/packages/supersonic-fe/`
+
+**Evaluation scripts:** Python scripts in `evaluation/` directory for Text2SQL accuracy testing.
+
+## Related Documentation
+
+- [README.md](README.md) - English documentation
+- [README_CN.md](README_CN.md) - Chinese documentation
+- [Evaluation Guide](evaluation/README.md) - Text2SQL evaluation process