WebUI Architecture Cleanup (#19541)

* webui: architecture foundation (non-MCP core refactors)

* chore: update webui build output

tools/server/webui/src/lib/constants/code.ts

@@ -0,0 +1,7 @@
+export const NEWLINE = '\n';
+export const DEFAULT_LANGUAGE = 'text';
+export const LANG_PATTERN = /^(\w*)\n?/;
+export const AMPERSAND_REGEX = /&/g;
+export const LT_REGEX = /</g;
+export const GT_REGEX = />/g;
+export const FENCE_PATTERN = /^```|\n```/g;