feat: Add C ABI for embedded seekdb (multi‑language SDKs)

[dengfuping]

Task Description

• Fix [Feature]: Stable C ABI for embedded seekdb (multi‑language SDKs) #104.

Solution Description

• Architecture Design:

Language Bindings (Node.js, Python, Rust, Go)
           │
           ▼
    SeekDB C ABI (seekdb.h/seekdb.cpp)
           │
           ▼
    OceanBase Core (liboceanbase.so)

• Source Code Directory (src/include/)

src/include/
├── seekdb.h                          # Public C API header file
│                                     # - All function declarations
│                                     # - Type definitions (SeekdbHandle, SeekdbResult, etc.)
│                                     # - Data structures (SeekdbBind, SeekdbField)
│                                     # - MySQL C API compatible interface
│
├── seekdb.cpp                        # C ABI implementation (~4800 lines)
│                                     # - Global initialization (seekdb_open/close)
│                                     # - Connection management
│                                     # - Query execution & Result set operations
│                                     # - Prepared Statement API
│                                     # - Signal handling & Stack management
│
├── CMakeLists.txt                    # Build configuration for libseekdb.so

Test Directory (unittest/include/)

unittest/include/
├── test_seekdb.cpp                   # C++ unit test suite (comprehensive)
│                                     # - Tests all C API functions directly
│                                     # - Complete API coverage
│
├── nodejs/                           # Node.js FFI binding (koffi)
│   ├── seekdb.js                    # FFI wrapper
│   ├── test.js                      # Test suite
│   └── test.sh                      # Test execution script
│
├── nodejs_napi/                      # Node.js N-API binding (native addon)
│   ├── seekdb.cpp                   # N-API C++ implementation
│   ├── test.js                      # Test suite
│   └── test.sh                      # Test execution script
│
├── python/                           # Python binding (ctypes)
│   ├── seekdb.py                    # FFI wrapper
│   ├── test.py                      # Test suite
│   └── test.sh                      # Test execution script
│
├── rust/                             # Rust FFI binding
│   ├── src/
│   │   ├── lib.rs                   # FFI bindings
│   │   └── test.rs                  # Test suite
│   └── test.sh                      # Test execution script
│
└── go/                               # Go binding (cgo)
    ├── seekdb/seekdb.go              # FFI wrapper
    ├── test.go                       # Test suite
    └── test.sh                       # Test execution script

Passed Regressions

• Unittest
• Node.js FFI bindings
• Node.js N-API bindings
• Python FFI bindings
• Go FFI bindings
• Rust FFI bindings

Build and test:

# build libseekdb library
./build.sh release --init -DBUILD_EMBED_MODE=ON --make

# unittest
make -j$(nproc) test_seekdb
cd build_release/unittest/include && ./test_seekdb

# bindings test
cd unittest/include/nodejs && bash ./test.sh
cd unittest/include/nodejs_napi && bash ./test.sh
cd unittest/include/python && bash ./test.sh
cd unittest/include/go && bash ./test.sh
cd unittest/include/rust && bash ./test.sh

Upgrade Compatibility

• Compatible

Other Information

• seekdb-js integration: feat: Integrate libseekdb to support embedded mode seekdb-js#7
• seekdb-rs integration: feat: Integrate libseekdb to support embedded mode ob-labs/seekdb-rs#4

Release Note

• 🆕 Add C ABI for embedded seekdb (multi‑language SDKs).