[xrfc]

Summary

Number.isInteger(Number(query)) accepts inputs such as 1e3, 1.0, and 5., but the subsequent BigInt(query) call in isSteamID64() rejects those strings. This makes the search endpoint return an error before it can search player names.

• Require a decimal digit string before entering the account-ID lookup, retaining the existing integer check and SteamID32/SteamID64 conversion.
• Let other inputs continue through the existing nickname-search path. The existing minimum nickname-query length remains unchanged.
• Add API regressions for all three reported inputs and a test that finds a player named 1e3, restoring the test fixture in finally.

Fixes #2992.

Validation

• npm run typecheck — passed.
• git diff --check — passed.
• 14 isolated cases using the actual applied search function and SteamID helpers, with database calls stubbed — passed. These cover reproduction against the old implementation, the three fixed inputs, numeric-looking nicknames, SteamID32/64 lookup, and edge cases.
• Full npm test has not been run locally because Docker is unavailable on this host. The suite requires PostgreSQL, Redis, Cassandra, MinIO, and parser services. The added HTTP regression tests still need the repository's integration CI.