TreasureRun v0.2.0-alpha — Server-hosted round flow

This alpha adds the first bounded server-hosted TreasureRun round flow while preserving the
distribution boundary established in v0.1.12-alpha.

Server-hosted flow

• One server-hosted session at a time.
• Two to eight participants.
• /treasurerun create, join, leave, start, stop, and status.
• create, start, and stop require the operator-only treasure.admin boundary.
• join and leave are player actions and are accepted only while the session is waiting.
• start locks an immutable participant snapshot, prepares one shared arena round, and uses a
  10-second countdown before RUNNING.
• Active-round stop, disconnect, disable, and preparation-failure paths converge on the shared
  cleanup/recovery boundary.
• Player-return obligations are persisted before participant teleport and are cleared only after
  successful return recovery.
• The published /gamestart compatibility path remains available and shares the authoritative
  round-lifecycle owner.

Verification represented by the release candidate

The authenticated release-candidate evidence covers:

• two-participant and eight-participant live server-hosted flows;
• duplicate and competing lifecycle operations;
• participant-disconnect, stop/disconnect, and disable/stop races;
• arena/chest/participant-teleport failure handling;
• process termination with same-data restart and reconnect recovery;
• protected-world safety checks.

Final clean-server, reproducible-build, packaging, and distribution checks remain release gates and
are not replaced by this release note.

Preserved boundaries

• The existing player quickstart and /gamestart route are not removed.
• 23 plugin-owned language YAML files and existing reviewed wording remain unchanged.
• ResourcePack/Fabric, database/ranking, and optional ProtocolLib boundaries are unchanged.
• The published v0.1.12-alpha tag, release notes, JAR, and release assets are not modified or
  republished.