feat(string/dedent): add dedent function for removing common leading whitespace

docs/ja/reference/string/dedent.md

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+# dedent
+
+複数行の文字列から各行の共通インデントを削除します。
+
+## インターフェース
+
+```typescript
+function dedent(str: string): string;
+function dedent(str: TemplateStringsArray, ...values: unknown[]): string;
+function dedent<T>(
+  tagFn: (strings: TemplateStringsArray, ...values: unknown[]) => T
+): (strings: TemplateStringsArray, ...values: unknown[]) => T;
+```
+
+### パラメータ
+
+- `str` (`string | TemplateStringsArray | Function`): インデントを削除する文字列、テンプレートリテラル、またはタグ関数。
+- `values` (`unknown[]`): タグ付きテンプレートリテラルとして使用する際に挿入する値。
+
+### 戻り値
+
+(`string | Function`): 共通インデントが削除された文字列、または合成されたタグ関数。
+
+## 例
+
+```typescript
+import { dedent } from 'es-toolkit/string';
+
+// 通常の関数として使用
+dedent('  hello\n  world');
+// 結果: 'hello\nworld'
+
+// タグ付きテンプレートリテラルとして使用
+dedent`
+  hello
+  world
+`;
+// 結果: 'hello\nworld'
+
+// 相対的なインデントを保持します
+dedent`
+  hello
+    world
+`;
+// 結果: 'hello\n  world'
+
+// 補間をサポートします
+const name = 'world';
+dedent`
+  hello
+  ${name}
+`;
+// 結果: 'hello\nworld'
+
+// タグ合成
+const html = dedent((strings, ...values) => strings.join(''));
+html` <div>Hello</div> `;
+// 結果: '<div>Hello</div>'
+```

docs/ko/reference/string/dedent.md

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+# dedent
+
+여러 줄 문자열에서 각 줄의 공통 들여쓰기를 제거해요.
+
+## 인터페이스
+
+```typescript
+function dedent(str: string): string;
+function dedent(str: TemplateStringsArray, ...values: unknown[]): string;
+function dedent<T>(
+  tagFn: (strings: TemplateStringsArray, ...values: unknown[]) => T
+): (strings: TemplateStringsArray, ...values: unknown[]) => T;
+```
+
+### 파라미터
+
+- `str` (`string | TemplateStringsArray | Function`): 들여쓰기를 제거할 문자열, 템플릿 리터럴, 또는 태그 함수예요.
+- `values` (`unknown[]`): 태그 템플릿 리터럴로 사용할 때 삽입할 값이에요.
+
+### 반환 값
+
+(`string | Function`): 공통 들여쓰기가 제거된 문자열, 또는 합성된 태그 함수를 반환해요.
+
+## 예시
+
+```typescript
+import { dedent } from 'es-toolkit/string';
+
+// 일반 함수로 사용
+dedent('  hello\n  world');
+// 결과: 'hello\nworld'
+
+// 태그 템플릿 리터럴로 사용
+dedent`
+  hello
+  world
+`;
+// 결과: 'hello\nworld'
+
+// 상대적인 들여쓰기를 유지해요
+dedent`
+  hello
+    world
+`;
+// 결과: 'hello\n  world'
+
+// 보간을 지원해요
+const name = 'world';
+dedent`
+  hello
+  ${name}
+`;
+// 결과: 'hello\nworld'
+
+// 태그 합성
+const html = dedent((strings, ...values) => strings.join(''));
+html` <div>Hello</div> `;
+// 결과: '<div>Hello</div>'
+```

docs/reference/string/dedent.md

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+# dedent
+
+Removes common leading whitespace from each line of a multi-line string.
+
+## Signature
+
+```typescript
+function dedent(str: string): string;
+function dedent(str: TemplateStringsArray, ...values: unknown[]): string;
+function dedent<T>(
+  tagFn: (strings: TemplateStringsArray, ...values: unknown[]) => T
+): (strings: TemplateStringsArray, ...values: unknown[]) => T;
+```
+
+### Parameters
+
+- `str` (`string | TemplateStringsArray | Function`): The string, template literal, or tag function to dedent.
+- `values` (`unknown[]`): The values to interpolate when used as a tagged template literal.
+
+### Returns
+
+(`string | Function`): The dedented string, or a dedented tag function when composed.
+
+## Examples
+
+```typescript
+import { dedent } from 'es-toolkit/string';
+
+// As a regular function
+dedent('  hello\n  world');
+// Returns: 'hello\nworld'
+
+// As a tagged template literal
+dedent`
+  hello
+  world
+`;
+// Returns: 'hello\nworld'
+
+// Preserves relative indentation
+dedent`
+  hello
+    world
+`;
+// Returns: 'hello\n  world'
+
+// Handles interpolations
+const name = 'world';
+dedent`
+  hello
+  ${name}
+`;
+// Returns: 'hello\nworld'
+
+// Tag composition
+const html = dedent((strings, ...values) => strings.join(''));
+html` <div>Hello</div> `;
+// Returns: '<div>Hello</div>'
+```

docs/zh_hans/reference/string/dedent.md

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+# dedent
+
+移除多行字符串中每行的公共前导空白。
+
+## 签名
+
+```typescript
+function dedent(str: string): string;
+function dedent(str: TemplateStringsArray, ...values: unknown[]): string;
+function dedent<T>(
+  tagFn: (strings: TemplateStringsArray, ...values: unknown[]) => T
+): (strings: TemplateStringsArray, ...values: unknown[]) => T;
+```
+
+### 参数
+
+- `str` (`string | TemplateStringsArray | Function`): 要移除缩进的字符串、模板字面量或标签函数。
+- `values` (`unknown[]`): 作为标签模板字面量使用时要插入的值。
+
+### 返回值
+
+(`string | Function`): 移除公共缩进后的字符串，或合成的标签函数。
+
+## 示例
+
+```typescript
+import { dedent } from 'es-toolkit/string';
+
+// 作为普通函数使用
+dedent('  hello\n  world');
+// 结果: 'hello\nworld'
+
+// 作为标签模板字面量使用
+dedent`
+  hello
+  world
+`;
+// 结果: 'hello\nworld'
+
+// 保留相对缩进
+dedent`
+  hello
+    world
+`;
+// 结果: 'hello\n  world'
+
+// 支持插值
+const name = 'world';
+dedent`
+  hello
+  ${name}
+`;
+// 结果: 'hello\nworld'
+
+// 标签合成
+const html = dedent((strings, ...values) => strings.join(''));
+html` <div>Hello</div> `;
+// 结果: '<div>Hello</div>'
+```

src/string/dedent.spec.ts

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+import { describe, expect, it } from 'vitest';
+import { dedent } from './dedent';
+
+describe('dedent', () => {
+  it('should remove common leading whitespace from each line', () => {
+    expect(dedent('  hello\n  world')).toBe('hello\nworld');
+  });
+
+  it('should preserve relative indentation', () => {
+    expect(dedent('  hello\n    world')).toBe('hello\n  world');
+  });
+
+  it('should handle a tagged template literal', () => {
+    const result = dedent`
+      hello
+      world
+    `;
+    expect(result).toBe('hello\nworld');
+  });
+
+  it('should preserve relative indentation in a tagged template literal', () => {
+    const result = dedent`
+      hello
+        world
+    `;
+    expect(result).toBe('hello\n  world');
+  });
+
+  it('should handle interpolations in a tagged template literal', () => {
+    const name = 'world';
+    const result = dedent`
+      hello
+      ${name}
+    `;
+    expect(result).toBe('hello\nworld');
+  });
+
+  it('should handle empty lines', () => {
+    const result = dedent`
+      hello
+
+      world
+    `;
+    expect(result).toBe('hello\n\nworld');
+  });
+
+  it('should handle a single line', () => {
+    expect(dedent('  hello')).toBe('hello');
+  });
+
+  it('should handle an empty string', () => {
+    expect(dedent('')).toBe('');
+  });
+
+  it('should handle a string with no indentation', () => {
+    expect(dedent('hello\nworld')).toBe('hello\nworld');
+  });
+
+  it('should handle tab indentation', () => {
+    expect(dedent('\t\thello\n\t\tworld')).toBe('hello\nworld');
+  });
+
+  it('should remove first and last empty lines', () => {
+    expect(dedent('\n  hello\n  world\n')).toBe('hello\nworld');
+  });
+
+  it('should handle lines with only whitespace', () => {
+    expect(dedent('  hello\n    \n  world')).toBe('hello\n\nworld');
+  });
+
+  it('should handle mixed indentation levels', () => {
+    expect(dedent('    a\n  b\n      c')).toBe('  a\nb\n    c');
+  });
+
+  it('should handle Windows line endings', () => {
+    expect(dedent('  hello\r\n  world')).toBe('hello\nworld');
+  });
+
+  it('should handle a string with only empty lines', () => {
+    expect(dedent('\n\n\n')).toBe('');
+  });
+
+  it('should compose with another tag function', () => {
+    const upper = (strings: TemplateStringsArray, ...values: unknown[]) => {
+      let result = '';
+      for (let i = 0; i < strings.length; i++) {
+        result += strings[i];
+        if (i < values.length) {
+          result += String(values[i]);
+        }
+      }
+      return result.toUpperCase();
+    };
+
+    const dedentedUpper = dedent(upper);
+    const result = dedentedUpper`
+      hello
+      world
+    `;
+    expect(result).toBe('HELLO\nWORLD');
+  });
+
+  it('should compose with another tag function and preserve interpolations', () => {
+    const identity = (strings: TemplateStringsArray, ...values: unknown[]) => {
+      let result = '';
+      for (let i = 0; i < strings.length; i++) {
+        result += strings[i];
+        if (i < values.length) {
+          result += String(values[i]);
+        }
+      }
+      return result;
+    };
+
+    const dedentedIdentity = dedent(identity);
+    const name = 'es-toolkit';
+    const result = dedentedIdentity`
+      Welcome to
+      ${name}!
+    `;
+    expect(result).toBe('Welcome to\nes-toolkit!');
+  });
+});