fix(privacy): generate invite QR locally instead of api.qrserver.com (H5)

The Share Room QR was fetched from the third-party api.qrserver.com, leaking
which rooms a user shares (and failing offline / under strict CSP). Now rendered
locally via qrcode.react (QRCodeSVG) — no network request, works offline. Added a
white quiet-zone container so the code scans on any theme; dropped the qrError
fallback (local generation can't fail the same way). Removed api.qrserver.com
from the prod CSP img-src (matrix repo). Build verified (rolldown interop OK).
Verification steps added to LOTUS_TESTING.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package-lock.json

@@ -57,6 +57,7 @@
         "millify": "6.1.0",
         "pdfjs-dist": "5.7.284",
         "prismjs": "1.30.0",
+        "qrcode.react": "4.2.0",
         "react": "19.2.6",
         "react-aria": "3.48.0",
         "react-blurhash": "0.3.0",
@@ -10758,6 +10759,15 @@
         "node": ">=6"
       }
     },
+    "node_modules/qrcode.react": {
+      "version": "4.2.0",
+      "resolved": "https://registry.npmjs.org/qrcode.react/-/qrcode.react-4.2.0.tgz",
+      "integrity": "sha512-QpgqWi8rD9DsS9EP3z7BT+5lY5SFhsqGjpgW5DY/i3mK4M9DTBNz3ErMi8BWYEfI3L0d8GIbGmcdFAS1uIRGjA==",
+      "license": "ISC",
+      "peerDependencies": {
+        "react": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0"
+      }
+    },
     "node_modules/raf-schd": {
       "version": "4.0.3",
       "resolved": "https://registry.npmjs.org/raf-schd/-/raf-schd-4.0.3.tgz",