fix(zen-mode): restore input history and watch replay (@byseif21) (monkeytypegame#6863)

### Description

fix:
* The result “input history” panel sometimes rendered nothing because
the renderer attempted to split an undefined target word.
added split word ?? "" to handle missing target words in zen.

* The replay view in zen mode could be empty if the last word was just
submitted (so input.current was empty at finish), and the replay words
list never got updated.

---------

Co-authored-by: Miodec <[email protected]>

Author: byseif21

frontend/src/ts/test/test-logic.ts

@@ -904,6 +904,12 @@ export async function finish(difficultyFailed = false): Promise<void> {
     Replay.replayGetWordsList(TestInput.input.getHistory());
   }
 
+  // in zen mode, ensure the replay words list reflects the typed input history
+  // even if the current input was empty at finish (e.g., after submitting a word).
+  if (Config.mode === "zen") {
+    Replay.replayGetWordsList(TestInput.input.getHistory());
+  }
+
   TestInput.forceKeyup(now); //this ensures that the last keypress(es) are registered
 
   const endAfkSeconds = (now - TestInput.keypressTimings.spacing.last) / 1000;

frontend/src/ts/test/test-ui.ts

@@ -1279,7 +1279,8 @@ async function loadWordsHistory(): Promise<boolean> {
         throw new Error("empty input word");
       }
 
-      const errorClass = input !== word ? "error" : "";
+      const errorClass =
+        Config.mode === "zen" ? "" : input !== word ? "error" : "";
 
       if (corrected !== undefined && corrected !== "") {
         const correctedChar = !containsKorean
@@ -1297,7 +1298,7 @@ async function loadWordsHistory(): Promise<boolean> {
       }
 
       const inputCharacters = Strings.splitIntoCharacters(input);
-      const wordCharacters = Strings.splitIntoCharacters(word);
+      const wordCharacters = Strings.splitIntoCharacters(word ?? "");
       const correctedCharacters = Strings.splitIntoCharacters(corrected ?? "");
 
       let loop;