fix: guard Icon src against non-function values to prevent crash

Add defensive check in folds Icon component so that if src is ever
undefined or non-function (root cause unknown, possibly data-dependent),
the SVG renders empty rather than throwing and crashing the whole app.

Also adds postinstall script to re-apply the patch after npm install.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "lotus-chat",
   "version": "4.12.1-lotus",
-  "description": "Lotus Chat — Matrix client for Lotus Guild",
+  "description": "Lotus Chat \u2014 Matrix client for Lotus Guild",
   "main": "index.js",
   "type": "module",
   "engines": {
@@ -18,7 +18,8 @@
     "typecheck": "tsc --noEmit",
     "prepare": "husky install",
     "commit": "git-cz",
-    "semantic-release": "semantic-release"
+    "semantic-release": "semantic-release",
+    "postinstall": "node scripts/patch-folds.mjs"
   },
   "lint-staged": {
     "*.{ts,tsx,js,jsx}": "eslint",