fix(addon-image): scan new columns on viewport width increase

viewportResize() should check whether cells in newly exposed columns
(oldCol + 1 through cols - 1) already have content before expanding
image tiles to the right. The loop used `rightCol > metrics.cols`,
which is false when widening (rightCol starts at oldCol + 1), so the
loop never ran, hasData stayed false, and tiles could overwrite cells
that already held text.

Use `rightCol < metrics.cols` so the emptiness check runs over the
intended column range.

Co-authored-by: Cursor <cursoragent@cursor.com>

addons/addon-image/src/ImageStorage.ts

@@ -531,7 +531,7 @@ export class ImageStorage implements IDisposable {
         }
         // expand only if right side is empty (nothing got wrapped from below)
         let hasData = false;
-        for (let rightCol = oldCol + 1; rightCol > metrics.cols; ++rightCol) {
+        for (let rightCol = oldCol + 1; rightCol < metrics.cols; ++rightCol) {
           if (line._data[rightCol * Cell.SIZE + Cell.CONTENT] & Content.HAS_CONTENT_MASK) {
             hasData = true;
             break;