test(escrow): add TTL refresh coverage for PlayerMatches index

[D-Ochuko]

closes #621

Extend TTL on PlayerMatches persistent storage in both the write path (create_match) and the read path (get_player_matches), and add two tests that assert the index TTL is reset to MATCH_TTL_LEDGERS after each operation.

Summary of changes:

• contracts/escrow/src/lib.rs — create_match: added extend_ttl for PlayerMatches after each set in the player loop. get_player_matches: extended TTL when the key exists before returning.
• contracts/escrow/src/tests.rs — added test_player_match_index_ttl_refreshes_on_append and test_player_match_indeto make the TTL decay observable before asserting it resets to
  MATCH_TTL_LEDGERS.

[drips-wave]

@D-Ochuko Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits