merge: upstream cinny v4.12.7 into lotus

Brings the 4.12.7 fixes: "%" sign wrapping below the composer input and
emoji autocompletion overwriting the preceding element. The release's
security half (sanitize-html, react-router-dom) was already applied in
91def3ad (we are on newer versions than upstream ships).

Resolved: kept our package.json/lockfile (the fork is ahead on every
dependency — React 19, router 7, i18next 26…), version 4.12.7-lotus, our
README/CONTRIBUTING, our "Lotus Chat vN" branding via pkg.version, and
the deleted GitHub-only workflows stay deleted. Note upstream announces
it is replacing matrix-js-sdk with its own SDK and pausing PRs; future
syncs will get harder.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "lotus-chat",
-  "version": "4.12.3-lotus",
+  "version": "4.12.7-lotus",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "lotus-chat",
-      "version": "4.12.3-lotus",
+      "version": "4.12.7-lotus",
       "hasInstallScript": true,
       "license": "AGPL-3.0-only",
       "dependencies": {