feat: Add Pydantic model support for TOON conversion

- Add encode_pydantic() to convert Pydantic models to TOON format
- Add decode_to_pydantic() to convert TOON back to Pydantic models
- Support both Pydantic v1 and v2
- Add options for exclude_unset, exclude_none, exclude_defaults, by_alias
- Fix decoder to handle top-level arrays correctly
- Add comprehensive tests for Pydantic integration
- Add pydantic usage examples
- Update README.md and README.zh-CN.md with Pydantic documentation
- Add pydantic as optional dependency in pyproject.toml

Author: VinciGit00

README.md

@@ -40,6 +40,11 @@ For development:
 pip install toonify[dev]
 ```
 
+With Pydantic support:
+```bash
+pip install toonify[pydantic]
+```
+
 ## Quick Start
 
 ### Python API
@@ -83,6 +88,48 @@ cat data.json | toon -e > data.toon
 toon data.json --stats
 ```
 
+### Pydantic Integration
+
+TOON supports direct conversion from Pydantic models:
+
+```python
+from pydantic import BaseModel
+from toon import encode_pydantic, decode_to_pydantic
+
+# Define Pydantic models
+class User(BaseModel):
+    id: int
+    name: str
+    email: str
+
+# Encode Pydantic models to TOON
+users = [
+    User(id=1, name='Alice', email='alice@example.com'),
+    User(id=2, name='Bob', email='bob@example.com')
+]
+
+toon = encode_pydantic(users)
+print(toon)
+# Output:
+# [2]{id,name,email}:
+#   1,Alice,alice@example.com
+#   2,Bob,bob@example.com
+
+# Decode TOON back to Pydantic models
+decoded_users = decode_to_pydantic(toon, User)
+assert all(isinstance(u, User) for u in decoded_users)
+```
+
+**Features:**
+- ✅ Direct conversion from Pydantic models (v1 and v2)
+- ✅ Support for nested models
+- ✅ Exclude unset, None, or default values
+- ✅ Field aliases support
+- ✅ Full validation on decode
+- ✅ Round-trip conversion
+
+See [examples/pydantic_usage.py](examples/pydantic_usage.py) for more examples.
+
 ## TOON Format Specification
 
 ### Basic Syntax
@@ -184,6 +231,57 @@ data = decode(toon_string, {
 })
 ```
 
+### `encode_pydantic(model, options=None, exclude_unset=False, exclude_none=False, exclude_defaults=False, by_alias=False)`
+
+Convert Pydantic model(s) to TOON string.
+
+**Parameters:**
+- `model`: Pydantic model instance or list of model instances
+- `options`: Same as `encode()` function
+- `exclude_unset`: If True, exclude fields that were not explicitly set
+- `exclude_none`: If True, exclude fields with None values
+- `exclude_defaults`: If True, exclude fields with default values
+- `by_alias`: If True, use field aliases instead of field names
+
+**Example:**
+```python
+from pydantic import BaseModel
+from toon import encode_pydantic
+
+class User(BaseModel):
+    id: int
+    name: str
+    email: str | None = None
+
+user = User(id=1, name='Alice')
+toon = encode_pydantic(user, exclude_none=True)
+```
+
+### `decode_to_pydantic(toon_string, model_class, options=None)`
+
+Decode TOON string to Pydantic model(s).
+
+**Parameters:**
+- `toon_string`: TOON formatted string
+- `model_class`: Pydantic model class to instantiate
+- `options`: Same as `decode()` function
+
+**Returns:**
+- Pydantic model instance or list of instances (depending on input)
+
+**Example:**
+```python
+from pydantic import BaseModel
+from toon import decode_to_pydantic
+
+class User(BaseModel):
+    id: int
+    name: str
+
+toon = "id: 1\nname: Alice"
+user = decode_to_pydantic(toon, User)
+```
+
 ## CLI Usage
 
 ```

README.zh-CN.md

@@ -36,6 +36,11 @@ pip install toonify
 pip install toonify[dev]
 ```
 
+支持Pydantic：
+```bash
+pip install toonify[pydantic]
+```
+
 ## 快速开始
 
 ### Python API
@@ -79,6 +84,48 @@ cat data.json | toon -e > data.toon
 toon data.json --stats
 ```
 
+### Pydantic集成
+
+TOON支持直接从Pydantic模型转换：
+
+```python
+from pydantic import BaseModel
+from toon import encode_pydantic, decode_to_pydantic
+
+# 定义Pydantic模型
+class User(BaseModel):
+    id: int
+    name: str
+    email: str
+
+# 将Pydantic模型编码为TOON
+users = [
+    User(id=1, name='Alice', email='alice@example.com'),
+    User(id=2, name='Bob', email='bob@example.com')
+]
+
+toon = encode_pydantic(users)
+print(toon)
+# 输出：
+# [2]{id,name,email}:
+#   1,Alice,alice@example.com
+#   2,Bob,bob@example.com
+
+# 将TOON解码回Pydantic模型
+decoded_users = decode_to_pydantic(toon, User)
+assert all(isinstance(u, User) for u in decoded_users)
+```
+
+**特性：**
+- ✅ 直接从Pydantic模型转换（支持v1和v2）
+- ✅ 支持嵌套模型
+- ✅ 排除未设置、None或默认值
+- ✅ 支持字段别名
+- ✅ 解码时完全验证
+- ✅ 往返转换
+
+详见[examples/pydantic_usage.py](examples/pydantic_usage.py)。
+
 ## TOON格式规范
 
 ### 基本语法
@@ -180,6 +227,57 @@ data = decode(toon_string, {
 })
 ```
 
+### `encode_pydantic(model, options=None, exclude_unset=False, exclude_none=False, exclude_defaults=False, by_alias=False)`
+
+将Pydantic模型转换为TOON字符串。
+
+**参数：**
+- `model`：Pydantic模型实例或模型实例列表
+- `options`：与`encode()`函数相同
+- `exclude_unset`：如果为True，排除未明确设置的字段
+- `exclude_none`：如果为True，排除None值字段
+- `exclude_defaults`：如果为True，排除具有默认值的字段
+- `by_alias`：如果为True，使用字段别名而不是字段名称
+
+**示例：**
+```python
+from pydantic import BaseModel
+from toon import encode_pydantic
+
+class User(BaseModel):
+    id: int
+    name: str
+    email: str | None = None
+
+user = User(id=1, name='Alice')
+toon = encode_pydantic(user, exclude_none=True)
+```
+
+### `decode_to_pydantic(toon_string, model_class, options=None)`
+
+将TOON字符串解码为Pydantic模型。
+
+**参数：**
+- `toon_string`：TOON格式字符串
+- `model_class`：要实例化的Pydantic模型类
+- `options`：与`decode()`函数相同
+
+**返回：**
+- Pydantic模型实例或实例列表（取决于输入）
+
+**示例：**
+```python
+from pydantic import BaseModel
+from toon import decode_to_pydantic
+
+class User(BaseModel):
+    id: int
+    name: str
+
+toon = "id: 1\nname: Alice"
+user = decode_to_pydantic(toon, User)
+```
+
 ## CLI使用
 
 ```