Mark 4.0.18 as released (#25641)

Update changelog and emscripten-version.txt [ci skip]

Author: emscripten-bot

ChangeLog.md

@@ -18,8 +18,11 @@ to browse the changes between the tags.
 
 See docs/process.md for more on how version tagging works.
 
-4.0.18 (in development)
+4.0.19 (in development)
 -----------------------
+
+4.0.18 - 10/24/25
+-----------------
 - The `emrun.py` script no longer support running on python2. (#25597)
 - `-sUSE_WEBGPU` was removed in favor of the external port Emdawnwebgpu which
   are used via `--use-port=emdawnwebgpu`. See 4.0.10 release notes for details.

emscripten-version.txt

@@ -1 +1 @@
-4.0.18-git
+4.0.19-git