refactor: drop formatting module and server-side schedule name mangling

Remove mangleDuplicateScheduleNames from saveUserData; keep schema validation only.

Co-authored-by: Kevin Wu <KevinWu098@users.noreply.github.com>

Author: cursoragent

apps/antalmanac/src/backend/lib/formatting.ts

@@ -1,7 +1,6 @@
 import { SESSION_COOKIE_NAME } from '$src/backend/context';
 import { oidcOAuthEnvSchema } from '$src/backend/env';
 import { ALLOWED_REDIRECT_URIS, isAllowedRedirectUri, oauthClientForRedirectUri } from '$src/backend/lib/auth/oauth';
-import { mangleDuplicateScheduleNames } from '$src/backend/lib/formatting';
 import { getCookiesFromHeader, getSafeAuthRedirectPath } from '$src/backend/lib/helpers';
 import { RDS } from '$src/backend/lib/rds';
 import { procedure, protectedProcedure, router } from '$src/backend/trpc';
@@ -255,7 +254,6 @@ const userDataRouter = router({
             }
 
             const userData = result.data;
-            userData.schedules = mangleDuplicateScheduleNames(userData.schedules);
 
             try {
                 return await RDS.upsertUserData(db, ctx.userId, userData);