Fix: no way to query all matches for a player

[yahia008]

Priority: Low
Estimated Time: 2 hours

Description:
There is no index mapping a player address to their match IDs. Frontends must scan all match IDs to find a player's matches, which is impractical at scale.

Tasks:

• Add DataKey::PlayerMatches(Address) storing a Vec<u64> of match IDs
• Update create_match to append the new match ID to both players' index entries
• Add get_player_matches(env: Env, player: Address) -> Vec<u64> read function
• Add test asserting the index is populated correctly after match creation

[theFirstCodeManiac]

@theFirstCodeManiac has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I’d love to take this on because this is a key scalability gap for frontend querying. I’ve implemented similar indexing patterns in smart contracts to avoid expensive scans.

I’m comfortable with Rust (Soroban), contract storage patterns, and testing.

I’ll add a PlayerMatches index, update create_match to maintain it for both players, expose a read function, and add tests to verify correctness.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @theFirstCodeManiac to this issue.

[Praxhant97]

@Praxhant97 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Greetings! I’d like to implement the PlayerMatches index to ensure the frontend can query match histories efficiently without expensive full-contract scans. I’m familiar with Soroban’s DataKey patterns and managing Vec storage for indexing. Kindly assign this to me so that I can start working on it. I have worked with similar issues earlier and am looking forward to working with you!
Time Required: ~2 hours

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Praxhant97 to this issue.