style: modernize sample code and tame clang-tidy noise

include/project/sample_library.hpp

@@ -5,18 +5,18 @@
 
 namespace project {
 
-// Greeter builds a greeting message for a given name.
-class Greeter {
-public:
-    explicit Greeter(std::string base = "Hello") : base_message_(std::move(base)) {}
+    // Greeter builds a greeting message for a given name.
+    class Greeter {
+    public:
+        explicit Greeter(std::string base = "Hello") : base_message_(std::move(base)) {}
 
-    [[nodiscard]] std::string greet(const std::string &name) const;
+    [[nodiscard]] auto greet(const std::string &name) const -> std::string;
 
-private:
-    std::string base_message_;
-};
+    private:
+        std::string base_message_;
+    };
 
-// generate_sequence returns numbers from 0 up to limit (exclusive).
-[[nodiscard]] std::vector<int> generate_sequence(int limit);
+    // generate_sequence returns numbers from 0 up to limit (exclusive).
+[[nodiscard]] auto generate_sequence(int limit) -> std::vector<int>;
 
-}  // namespace project
+} // namespace project