[SSOrangeCATY]

Summary

• Restore deathmatch reconnects to active combat, respawn protection, and starting kits without resetting match statistics.
• Restore map identity, team definitions, and player statistics after the outer login event clears client state.
• Preserve spectator joins and exclude spectators from match initialization and combat respawn callbacks.
• Reject missing-spawn-point starts before clearing lobby, inventory, or ready state.
• Guard delayed death/respawn callbacks after departure or match completion and clear stale deathmatch state between matches.
• Add deathmatch lifecycle and shop/listener-editor integration GameTests and update deathmatch documentation.
• Update the FPSMatch submodule to the companion modern editor PR.

Validation

• ./gradlew build runGameTestServer: passed on top of the current master.
• All 40 required Forge GameTests passed, including 8 new deathmatch regression tests and the existing master refund regression tests.
• FPSMatch standalone build, Spotless checks, and all 5 JUnit tests passed.

Merge order

Merge PhasetransCrystal/FPSMatch#46 first, then this PR. The submodule points to that PR's tested commit.