fix(search): use numeric for-loop instead of for-in on positions array

for (var i in positions) yields string keys ("0", "1", ...),
causing j = i + 1 to produce "01" (string concatenation) instead
of 1 (numeric addition). This made the inner while-loop skip
positions[1] for i=0 and exit immediately for all other starting
indices, so the algorithm always selected the first match's window
regardless of where the densest cluster was.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

assets/js/search_functions.js

@@ -67,7 +67,7 @@ function getBlurbForResult(result, item, positions) {
     // Calculate the best section of the content to blurb
     var best_i = -1;
     var best_n = 0;
-    for (var i in positions) {
+    for (var i = 0; i < positions.length; i++) {
         var n = 1;
         var j = i+1;
         while (j < positions.length) {