chore(highscores): align dependency and lint standards

Update the high-score service to the latest compatible direct releases while
keeping the requested Cargo.toml ranges: 0.x crates use their latest minor
line and 1.x crates use their major-only range. Refresh the standalone lockfile
so it resolves axum 0.8.9, rusqlite 0.40.2, serde 1.0.229, serde_json 1.0.151,
Tokio 1.53.1, and the latest dev-tool releases.

Copy the main package's Clippy policy and make the repository's formatting
recipes cover the service. The nested crate inherits the parent rustfmt.toml,
so one configuration remains authoritative; newly required documentation and
borrow style also keep the stricter pedantic policy clean.

Test Plan:
- `cargo update --manifest-path highscore-server/Cargo.toml` -- passed
- `just test` -- passed (3 service tests and 137 game tests)
- `just clippy` -- passed with the shared lint policy
- `just fmt-highscore-server` and `cargo +nightly fmt --manifest-path highscore-server/Cargo.toml -- --check` -- passed
- `cargo tree --manifest-path highscore-server/Cargo.toml --depth 1` -- confirmed latest direct resolutions
- `rustfmt +nightly --print-config current` -- confirmed the parent rustfmt settings
- `rumdl check --flavor commonmark highscore-server/README.md` -- passed
- `git diff --cached --check` -- passed

tdkpin-rs/highscore-server/src/lib.rs

@@ -39,10 +39,21 @@ impl From<rusqlite::Error> for StoreError {
 pub struct HighScoreStore(Arc<Mutex<Connection>>);
 
 impl HighScoreStore {
+    /// Open or create a SQLite-backed high-score store.
+    ///
+    /// # Errors
+    ///
+    /// Returns the SQLite error raised while opening or initializing the
+    /// database.
     pub fn open(path: impl AsRef<Path>) -> Result<Self, rusqlite::Error> {
         Self::from_connection(Connection::open(path)?)
     }
 
+    /// Create an in-memory high-score store for tests or short-lived runs.
+    ///
+    /// # Errors
+    ///
+    /// Returns the SQLite error raised while initializing the database.
     pub fn open_in_memory() -> Result<Self, rusqlite::Error> {
         Self::from_connection(Connection::open_in_memory()?)
     }
@@ -60,6 +71,11 @@ impl HighScoreStore {
         Ok(Self(Arc::new(Mutex::new(connection))))
     }
 
+    /// Return the current table in descending score order.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the database lock or query fails.
     pub fn list(&self) -> Result<Vec<HighScore>, StoreError> {
         let connection = self.0.lock().map_err(|_| StoreError::Poisoned)?;
         let mut statement = connection.prepare(
@@ -83,6 +99,11 @@ impl HighScoreStore {
         Ok(scores)
     }
 
+    /// Add one score and return the resulting canonical top ten.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the database lock or transaction fails.
     pub fn submit(&self, entry: &HighScore) -> Result<Vec<HighScore>, StoreError> {
         {
             let mut connection = self.0.lock().map_err(|_| StoreError::Poisoned)?;
@@ -125,7 +146,7 @@ fn invalid_request(message: &'static str) -> Response {
         .into_response()
 }
 
-fn validate_request(request: SubmitRequest) -> Result<HighScore, &'static str> {
+fn validate_request(request: &SubmitRequest) -> Result<HighScore, &'static str> {
     let name = request.name.trim();
     if name.is_empty() {
         return Err("name must not be empty");
@@ -157,7 +178,7 @@ async fn submit_high_score(
     State(store): State<HighScoreStore>,
     Json(request): Json<SubmitRequest>,
 ) -> Response {
-    let entry = match validate_request(request) {
+    let entry = match validate_request(&request) {
         Ok(entry) => entry,
         Err(message) => return invalid_request(message),
     };