fix: restore player metadata sync in gather_extra_info()

[wnkz]

Summary

• Restores player metadata population in gather_extra_info() that was removed in Mega bugfix #311, fixing a v0.41.0 regression on overtime demos
• Fixes null victim damage events, incorrect side attribution, and missing player rounds caused by stale self.players when fullpackets are skipped or delta updates don't trigger PlayerConnect events
• handle_player_connect() is kept as-is (the redundant self.players.insert() is idempotent)

Fixes #314

Test plan

• cargo build compiles cleanly
• cargo test — all 333 tests pass
• Parse overtime demo from v0.41.0 regression: incorrect damage attribution and missing player rounds in overtime demos #314 and verify:
  • All 10 players appear in all 30 rounds
  • No damage events with null victim_name/victim_steamid
  • ADR values match v0.40.3
  • Team attribution is correct (attacker_side != victim_side filter gives expected ADR)

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