Arcadia Spawn Dimension

### Added

- **arcadia-lib Integration** — Full integration with arcadia-lib ecosystem. Hub card registered at first position. Uses ArcadiaMessages for themed messaging, TeleportManager for warmup/cooldown teleports.

- **Debug Command Suite** — 13 diagnostic subcommands under `/arcadia_spawn debug`: status, spawn, dimension, lobbies, rtp, config, slots, player, reload_all, reset_visited, tps, lang.

- **Teleport Warmup & Cooldown** — All teleports (/spawn, /lobby, /arcadiartp) now support configurable warmup delays and cooldowns via arcadia-lib TeleportManager with movement cancellation.

- **Enhanced Configuration** — New config options: `force_spawn_on_first_join`, `force_spawn_on_respawn`, `rtp_cooldown_seconds`, `rtp_warmup_ticks`, `rtp_max_attempts`, `spawn_tp_warmup_ticks`, `spawn_tp_cooldown_seconds`, `lobby_tp_warmup_ticks`, `lobby_tp_cooldown_seconds`.

- **Lobby Menu UX** — Glass pane borders, bilingual lore text ("Click to teleport | Cliquez pour vous tp").

### Changed

- **Package** — Moved from `com.vyrriox.arcadiaspawn` to `com.arcadia.spawn` for ecosystem consistency.

- **Build System** — Migrated from `net.neoforged.gradle.userdev` to `net.neoforged.moddev` 2.0.140. Added arcadia-lib 1.2.0 as dependency.

- **Side** — Changed from server-only to BOTH (client + server) for Hub integration.

- **Command Structure** — Admin commands consolidated under `/arcadia_spawn` (was `/arcadialobby`). Player commands `/lobby`, `/spawn`, `/arcadiartp` unchanged.

- **Config Paths** — Moved from `config/arcadia/arcadialobbyspawn/` to `config/arcadia/spawn/`. Lobby data now in `config/arcadia/spawn/lobbies/`.

- **Mixin Config** — Renamed from `arcadiaspawn.mixins.json` to `arcadia_spawn.mixins.json`.

- **NeoForge Version** — Updated to 21.1.219.

### Fixed

- **Spawn Dimension Bug** — `/setlobbyspawn` and `/arcadia_spawn setspawn` now store the dimension alongside coordinates. The spawn teleport correctly targets the dimension where spawn was set, not just `arcadia:spawn`. This prevents wrong-dimension teleports when spawn is set outside the spawn dimension.

- **Respawn Bug** — Players dying without a bed/anchor are now correctly teleported to the configured spawn point instead of world spawn. Uses `server.execute()` to schedule after respawn completion.

- **FTB Essentials /back Compatibility** — All teleportations now fire `EntityTeleportEvent.TeleportCommand` before executing, allowing FTB Essentials and other mods to record the pre-teleport position for `/back`.

- **RTP Thread Safety** — Replaced `java.util.Random` with `ThreadLocalRandom` to eliminate synchronization contention.

- **Kick Message** — Slot bypass kick message now bilingual by default (EN | FR).

### Performance

- **ThreadLocalRandom** — RTP safe position search uses lock-free random for better throughput.

- **Configurable RTP Attempts** — `rtp_max_attempts` limits worst-case chunk loading (default 50).

- **Zero Tick Handlers** — Mod registers no tick listeners. All logic is event-driven.

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### Ajouts

- **Integration arcadia-lib** — Integration complete avec l'ecosysteme arcadia-lib. Carte Hub en premiere position. Utilise ArcadiaMessages pour les messages themes, TeleportManager pour les teleportations avec warmup/cooldown.

- **Suite de Commandes Debug** — 13 sous-commandes de diagnostic sous `/arcadia_spawn debug` : status, spawn, dimension, lobbies, rtp, config, slots, player, reload_all, reset_visited, tps, lang.

- **Warmup & Cooldown de Teleportation** — Toutes les teleportations (/spawn, /lobby, /arcadiartp) supportent maintenant des delais de warmup et cooldowns configurables via le TeleportManager d'arcadia-lib avec annulation sur mouvement.

- **Configuration Etendue** — Nouvelles options : `force_spawn_on_first_join`, `force_spawn_on_respawn`, `rtp_cooldown_seconds`, `rtp_warmup_ticks`, `rtp_max_attempts`, etc.

- **UX Menu Lobby** — Bordures en vitres, texte de lore bilingue.

### Modifications

- **Package** — Deplacement de `com.vyrriox.arcadiaspawn` vers `com.arcadia.spawn`.

- **Systeme de Build** — Migration vers `net.neoforged.moddev` 2.0.140 avec arcadia-lib 1.2.0.

- **Side** — Passe de serveur uniquement a BOTH (client + serveur) pour l'integration Hub.

- **Structure des Commandes** — Commandes admin sous `/arcadia_spawn` (etait `/arcadialobby`). `/lobby`, `/spawn`, `/arcadiartp` inchanges.

- **Chemins de Config** — Deplaces de `config/arcadia/arcadialobbyspawn/` vers `config/arcadia/spawn/`.

### Correctifs

- **Bug Dimension Spawn** — `/setlobbyspawn` et `/arcadia_spawn setspawn` stockent maintenant la dimension avec les coordonnees. La teleportation cible correctement la dimension ou le spawn a ete defini.

- **Bug Respawn** — Les joueurs mourant sans lit/ancre sont maintenant correctement teleportes au spawn configure au lieu du world spawn. Utilise `server.execute()` pour planifier apres la fin du respawn.

- **Compatibilite FTB Essentials /back** — Toutes les teleportations declenchent maintenant `EntityTeleportEvent.TeleportCommand` avant execution, permettant a FTB Essentials et autres mods d'enregistrer la position pre-teleportation pour `/back`.

- **Thread Safety RTP** — Remplacement de `java.util.Random` par `ThreadLocalRandom`.

- **Message de Kick** — Message de kick bilingue par defaut (EN | FR).

### Performance

- **ThreadLocalRandom** — Recherche de position RTP sans verrou pour un meilleur debit.

- **Tentatives RTP Configurables** — `rtp_max_attempts` limite le chargement de chunks worst-case.

- **Zero Tick Handlers** — Le mod n'enregistre aucun listener de tick. Tout est evenementiel.