WebUI Architecture Cleanup (#19541)

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

* chore: update webui build output

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

@@ -0,0 +1,8 @@
+export const MS_PER_SECOND = 1000;
+export const SECONDS_PER_MINUTE = 60;
+export const SECONDS_PER_HOUR = 3600;
+export const SHORT_DURATION_THRESHOLD = 1;
+export const MEDIUM_DURATION_THRESHOLD = 10;
+
+/** Default display value when no performance time is available */
+export const DEFAULT_PERFORMANCE_TIME = '0s';