[code][fix] improvements for LAN 202503

- more robust client <-> server connection
  - new client event: DownloadGameFilesFailed
  - 3 seconds to reconnect
  - retry forever if server is gone and never lose a UI request

- code cleanup here and there (mostly server)

crates/lanspread-db/src/db.rs

@@ -152,13 +152,22 @@ pub struct GameFileDescription {
     pub is_dir: bool,
 }
 
+impl GameFileDescription {
+    #[must_use]
+    pub fn is_version_ini(&self) -> bool {
+        self.relative_path.ends_with("/version.ini")
+    }
+}
+
 impl fmt::Debug for GameFileDescription {
     #[allow(clippy::cast_precision_loss)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
-            "game:{} path:{} dir:{}",
-            self.game_id, self.relative_path, self.is_dir
+            "{}: [{}] path:{}",
+            self.game_id,
+            if self.is_dir { 'D' } else { 'F' },
+            self.relative_path,
         )
     }
 }