fix(labs): SVG markup rendered as text in 6 simulations

Hardcoded inline <svg class="ic"> markers used as arrow replacements

(left over from emoji removal) were displayed as raw HTML text where

the consumer used textContent or canvas fillText:

- chemsandbox: csbar-v5 (Продукты cell) used textContent → SVG visible.

  Switched to innerHTML for consistency with eq/ionNet cells.

  Quiz question (qEl.textContent) and answer also receiving SVG —

  cleaned via _csClean at source.

- reactions: modeTxt drawn via canvas fillText — replaced SVG with →.

- ionexchange: REACTIONS data + canvas labels — bulk SVG → Unicode arrows.

- newton: action button labels used textContent → switched to innerHTML;

  canvas arrow labels: SVG → Unicode →/↓.

- collision: 'KE сохранена' canvas label — SVG checkmark → ✓.

- projectile: canvas badges + textContent wind label — SVG → Unicode ←/→/↩.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/js/labs/chemsandbox.js

@@ -1585,7 +1585,7 @@ class ChemSandboxSim {
     if (rx.fx.gas) {
       questions.push(`Получи газ ${rx.fx.gas}`);
     }
-    questions.push(`Проведи реакцию: ${prods}`);
+    questions.push(`Проведи реакцию: ${_csClean(prods)}`);
     if (rx.type === 'Нейтрализация') {
       questions.push('Проведи реакцию нейтрализации');
     }
@@ -1622,7 +1622,7 @@ class ChemSandboxSim {
         score:    this._quizScore,
         total:    this._quizTotal,
         result:   this._quizResult,
-        answer:   this._quizTask ? this._quizTask.rx.eq : null,
+        answer:   this._quizTask ? _csClean(this._quizTask.rx.eq) : null,
       });
     }
   }
@@ -1821,7 +1821,9 @@ class ChemSandboxSim {
     const eqEl = document.getElementById('csbar-v4');
     eqEl.innerHTML = info.equation || '—';
     eqEl.title = (info.equation || '').replace(/<[^>]*>/g, '');
-    document.getElementById('csbar-v5').textContent = info.products || '—';
+    const prodEl = document.getElementById('csbar-v5');
+    prodEl.innerHTML = info.products || '—';
+    prodEl.title = (info.products || '').replace(/<[^>]*>/g, '');
     const ionEl = document.getElementById('csbar-v6');
     ionEl.innerHTML = info.ionNet || '—';
     ionEl.title = (info.ionNet || '').replace(/<[^>]*>/g, '');