docs: scope the foreign-script and surefire claims to what the code does

hasForeignScript detects by alphabet, so Latin-script leakage such as
the observed French "contiennent" is not caught. Say so in the javadoc
and admit the gap in the design doc rather than implying coverage.

failIfNoTests catches a misplaced or misnamed test class, not a
disabled one: an @Disabled class still reports as skipped and the
build stays green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F3jSvSTrG4qsniLSr6TpC6

src/main/java/dev/marcospaulo/canalhandia/AiText.java

@@ -11,8 +11,8 @@ import java.util.regex.Pattern;
 final class AiText {
 
     /**
-     * Scripts that should never appear in a Portuguese answer. The model has
-     * been observed dropping single Chinese words mid-sentence.
+     * Non-Latin scripts that should never appear in a Portuguese answer. The
+     * model has been observed dropping single Chinese words mid-sentence.
      */
     private static final Pattern FOREIGN = Pattern.compile(
             "[\\p{IsHan}\\p{IsHiragana}\\p{IsKatakana}\\p{IsHangul}\\p{IsCyrillic}\\p{IsArabic}]");
@@ -20,6 +20,15 @@ final class AiText {
     private AiText() {
     }
 
+    /**
+     * True if the text contains a character from a non-Latin script.
+     *
+     * <p>This detects leakage by alphabet, so it catches only what a different
+     * alphabet makes visible. A foreign word written in Latin script is
+     * <b>not</b> caught: the French {@code contiennent}, observed in an
+     * otherwise Portuguese reply, passes this check. Catching that would need
+     * dictionary or language-identification work this method does not do.
+     */
     static boolean hasForeignScript(String text) {
         return text != null && FOREIGN.matcher(text).find();
     }