Add comprehensive shell test suite for Serena MCP server multi-language support

[Copilot]

Validates that ghcr.io/githubnext/serena-mcp-server:latest correctly supports Go, Java, JavaScript, and Python through the MCP protocol using stdio communication.

Test Script (test_serena.sh - 488 lines)

• 20+ test cases across 13 sections: infrastructure, language runtimes, MCP protocol, language-specific analysis (symbols/diagnostics), error handling
• Sends JSON-RPC requests over stdin, validates responses against known sample codebases
• Color-coded output, JSON response logging, success rate calculation
• Exit codes for CI/CD integration

# Usage
./test/serena-mcp-tests/test_serena.sh
SERENA_IMAGE="serena-mcp-server:local" ./test/serena-mcp-tests/test_serena.sh

Sample Codebases

Four Calculator implementations with known symbols for validation:

• Go: 3 files (Calculator type, Add/Multiply methods, utilities)
• Java: 2 files (Calculator class, Utils with JavaDoc)
• JavaScript: 3 files (Calculator class, CommonJS exports)
• Python: 2 files (Calculator with type hints, docstrings)

Tests validate each language server can:

• Find symbols (functions, classes, methods)
• Run diagnostics
• Handle initialization and tool listing

Documentation

• README.md (265 lines): Complete reference with test categories, troubleshooting, extension guidelines
• QUICKSTART.md (159 lines): Quick start and common issues
• expected/README.md (120 lines): Expected MCP response structures

Structure

test/serena-mcp-tests/
├── test_serena.sh           # Main test script
├── README.md                # Complete documentation
├── QUICKSTART.md           # Quick start guide
├── expected/               # Expected response formats
└── samples/                # Sample codebases
    ├── go_project/
    ├── java_project/
    ├── js_project/
    └── python_project/

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