Files view: drop the ASCII column from the change-details hex views

- the modal's hex views carried a 16-byte ASCII column per row; file data is
  rarely text and the column halved the room for the two before/after views,
  so it is gone: `hexImageRows` no longer builds an `ascii` field,
  `hexImageHtml` no longer emits it and the `.hex-ascii` CSS rule is removed
- tests: the hex-row test asserts the field is gone (so it cannot come back
  silently); README/README_RUS wording updated
- SW cache simtrace-analyser-v67 (cosmetic, no version bump)

frontend/index.html

@@ -204,7 +204,6 @@ body { font: 14px/1.5 system-ui, sans-serif; background: var(--bg); color: var(-
 .hex-cell.hex-changed { background: var(--warn); color: #1a1a1a; font-weight: 600; }
 .hex-cell.hex-new { background: var(--accent); color: #fff; font-weight: 600; }
 .hex-cell.hex-unknown { color: var(--text-muted); }
-.hex-ascii { color: var(--text-muted); margin-left: 8px; }
 .hex-note { font-size: 12px; color: var(--text-muted); margin-top: 6px; }
 .hex-error { font-size: 12px; color: var(--error); }
 .map-item { padding: 3px 8px; cursor: pointer; border-radius: 4px; font-size: 13px; color: var(--text); word-break: break-word; }
@@ -2136,22 +2135,18 @@ function hexImageRows(segments, ranges, observed, limit) {
             break;
         }
         const cells = [];
-        let ascii = '';
         for (let i = 0; i < 16; i++) {
             const pos = off + i;
             const hex = bytes.get(pos);
             if (hex === undefined) {
                 cells.push({hex: '--', cls: 'hex-unknown'});
-                ascii += ' ';
                 continue;
             }
             const cls = covered(ranges, pos) ? 'hex-changed'
                 : covered(observed, pos) ? 'hex-new' : '';
-            const value = parseInt(hex, 16);
             cells.push({hex: hex, cls: cls});
-            ascii += (value >= 0x20 && value < 0x7f) ? String.fromCharCode(value) : '.';
         }
-        rows.push({offset: off, cells: cells, ascii: ascii});
+        rows.push({offset: off, cells: cells});
     }
     return {rows: rows, truncated: truncated, end: end};
 }
@@ -2162,7 +2157,7 @@ function hexImageHtml(image, key) {
     const body = view.rows.map(r =>
         `<div class="hex-row"><span class="hex-addr">${r.offset.toString(16).toUpperCase().padStart(4, '0')}</span>` +
         r.cells.map(c => `<span class="hex-cell ${c.cls}">${c.hex}</span>`).join('') +
-        `<span class="hex-ascii">${escapeHtml(r.ascii)}</span></div>`
+        '</div>'
     ).join('') || `<div class="hex-row hex-unknown">${t('never observed')}</div>`;
     return `<div class="hex-view">${body}</div>` +
         (view.truncated ? `<div class="hex-note">${t('Showing the first {n} bytes of the image').replace('{n}', 2048)}</div>` : '');