The project uses express@^4.18.3 at runtime but had @types/express@^5.0.6
as type definitions. The v5 types widened ParamsDictionary from
string to string | string[], causing 115 type errors across all route
handlers.
Fix: downgrade @types/express to ^4.17.25 (latest v4), which correctly
types req.params as string — matching Express 4 runtime behaviour.
Removes the StringParams = Record<string, string> workaround from
types.ts and the Request<StringParams> annotations from all 15 route
files that were introduced as a workaround for the type mismatch.
3d33191925