Run cargo clippy on CI (#281)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit


- **新機能**
  - ワークフローに`cargo clippy`を指定したオプションで実行する「Clippy (lint)」ステップを追加しました。

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.github/workflows/build.yml

@@ -10,6 +10,8 @@ on:
 
 env: 
   CARGO_TERM_COLOR: always    
+  # Make sure CI fails on all warnings, including Clippy lints
+  RUSTFLAGS: "-Dwarnings"
 
 permissions:
   contents: read
@@ -32,3 +34,5 @@ jobs:
         run: mkdir -p app/build
       - name: Build App
         run: cargo build --verbose --package app
+      - name: Clippy (lint)
+        run: cargo clippy --all-targets --all-features

app/src-tauri/Cargo.toml

@@ -2,12 +2,10 @@
 name = "app"
 version.workspace = true
 description = "A Tauri App"
-authors = ["you"]
+authors.workspace = true
 license = ""
-repository = ""
 default-run = "app"
 edition = "2021"
-rust-version = "1.60"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html