fix: return actual success from checkIntoMatch and validate relay fragment params

[Flegma]

Summary

• checkIntoMatch: Was always returning success: false regardless of outcome. Now returns true when the player's check-in mutation affects rows.
• match-relay controller: Replaced raw parseInt(fragment) with NestJS ParseIntPipe — returns 400 Bad Request on non-numeric fragment values instead of passing NaN downstream.

Note: The veto condition at line 455 was reviewed and found to be correct (uses && within branches, || between them). No change needed.

Test plan

• Check into a match as a player — API returns success: true
• Check into match with invalid state — returns error as before
• Access relay with valid fragment number — works normally
• Access relay with non-numeric fragment (e.g., abc) — returns 400

Closes 5stackgg/5stack-panel#380

[lukepolo]

we need to test this, it may actually be a string. test via enabling relay

[Flegma]

Checked the relay service — getStart, getFragment, and postField all accept fragmentIndex: number, so ParseIntPipe is type-compatible.

The difference: before, a non-numeric fragment would pass NaN to the service silently. Now it returns 400 Bad Request instead.

Happy to test with relay enabled, or revert to parseInt with an explicit NaN check if you prefer a safer rollout. Let me know.

[lukepolo]

yah we will need to actually test this live. cause just cause the type says its an int,doesnt mean its an int :-)