Add Rust install hyperlink to all documentation (#14)

Link to https://rust-lang.org/tools/install/ in all "Requires Rust 1.86+" mentions across README.md, CONTRIBUTING.md, and all 6 i18n documentation files.

Co-authored-by: Claude Haiku 4.5 <noreply@anthropic.com>

Author: MatrixA

CONTRIBUTING.md

@@ -19,7 +19,7 @@ cargo test
 cargo run -- check photo.jpg
 ```
 
-Requires **Rust 1.86+**.
+Requires [**Rust 1.86+**](https://rust-lang.org/tools/install/).
 
 ## Before Submitting a PR
 

README.md

@@ -29,7 +29,7 @@ AICheck answers these questions by analyzing file metadata and invisible waterma
 cargo install aicheck
 ```
 
-> Requires Rust 1.86+. Or build from source: `cargo install --path .`
+> Requires [Rust 1.86+](https://rust-lang.org/tools/install/). Or build from source: `cargo install --path .`
 
 ```bash
 aic check photo.jpg

docs/README.de.md

@@ -29,7 +29,7 @@ AICheck beantwortet diese Fragen durch Analyse von Datei-Metadaten und unsichtba
 cargo install aicheck
 ```
 
-> Erfordert Rust 1.86+. Oder aus dem Quellcode bauen: `cargo install --path .`
+> Erfordert [Rust 1.86+](https://rust-lang.org/tools/install/). Oder aus dem Quellcode bauen: `cargo install --path .`
 
 ```bash
 aic check photo.jpg

docs/README.es.md

@@ -29,7 +29,7 @@ AICheck responde estas preguntas analizando los metadatos de archivos y marcas d
 cargo install aicheck
 ```
 
-> Requiere Rust 1.86+. O compilar desde el código fuente: `cargo install --path .`
+> Requiere [Rust 1.86+](https://rust-lang.org/tools/install/). O compilar desde el código fuente: `cargo install --path .`
 
 ```bash
 aic check photo.jpg

docs/README.hi.md

@@ -29,7 +29,7 @@ AICheck फ़ाइल मेटाडेटा और अदृश्य व
 cargo install aicheck
 ```
 
-> Rust 1.86+ आवश्यक। सोर्स से बिल्ड करें: `cargo install --path .`
+> [Rust 1.86+](https://rust-lang.org/tools/install/) आवश्यक। सोर्स से बिल्ड करें: `cargo install --path .`
 
 ```bash
 aic check photo.jpg

docs/README.ja.md

@@ -29,7 +29,7 @@ AICheckはファイルのメタデータと不可視ウォーターマークを
 cargo install aicheck
 ```
 
-> Rust 1.86+が必要です。ソースからビルド：`cargo install --path .`
+> [Rust 1.86+](https://rust-lang.org/tools/install/)が必要です。ソースからビルド：`cargo install --path .`
 
 ```bash
 aic check photo.jpg

docs/README.ko.md

@@ -29,7 +29,7 @@ AICheck는 파일 메타데이터와 보이지 않는 워터마크를 분석하
 cargo install aicheck
 ```
 
-> Rust 1.86+ 필요. 소스에서 빌드: `cargo install --path .`
+> [Rust 1.86+](https://rust-lang.org/tools/install/) 필요. 소스에서 빌드: `cargo install --path .`
 
 ```bash
 aic check photo.jpg

docs/README.zh-CN.md

@@ -29,7 +29,7 @@ AICheck 通过分析文件元数据和隐形水印来回答这些问题。不需
 cargo install aicheck
 ```
 
-> 需要 Rust 1.86+。从源码构建：`cargo install --path .`
+> 需要 [Rust 1.86+](https://rust-lang.org/tools/install/)。从源码构建：`cargo install --path .`
 
 ```bash
 aic check photo.jpg