feat: chef commands moved to admin + PlaceholderAPI integration

Chef → admin: the chef role no longer grants any command privilege.
All team-management subcommands now take <team> as an argument and are
gated by their crcore.team.<action> permission only:
- add <team> <player>
- remove <team> <player>
- transfer <team> <player>
- visibility <team> <PUBLIC|PRIVATE>
- setspawn <team> (still player-only — needs admin's location)

The LEADER role is kept in the data model (Team / TeamMember) and remains
usable by game plugins via the API, but does not unlock any default
command. Future work can re-introduce chef-specific commands if needed.

PlaceholderAPI: auto-detected at CRCore.enable(). If the PAPI plugin is
present on the server, CRCorePlaceholderExpansion registers automatically;
otherwise the lib runs without it (no NoClassDefFoundError thanks to the
indirection through doRegisterPlaceholderHook).

Placeholders exposed:
- Team: %crcore_team%, %crcore_team_name/tag/color/color_chat/size/
  visibility/leader_name/total_score%, %crcore_team_score_<name>%
- Player: %crcore_player_score_<name>%, %crcore_player_score_total%

Dependency: me.clip:placeholderapi:2.11.6, scope provided. New repo:
https://repo.extendedclip.com/content/repositories/placeholderapi/.

docs/features.md, decisions.md and the builtin-commands diagram updated to
reflect the simpler admin/player two-tier model and the PAPI section.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/diagrams/builtin-commands-diagram.puml

@@ -1,5 +1,5 @@
 @startuml builtin-commands-diagram
-title CR-Core — Default /core team commands (admin / chef / joueur)
+title CR-Core — Default /core team commands (admin / joueur)
 
 skinparam classAttributeIconSize 0
 hide empty members
@@ -11,16 +11,13 @@ package "fr.luc.crcore.command" {
 
 package "fr.luc.crcore.command.builtin" {
 
-  class CoreCommand {
-    + CoreCommand(teamSvc, playerSvc)
-  }
+  class CoreCommand
   CoreCommand --|> BaseCommand
 
   package "fr.luc.crcore.command.builtin.team" {
 
     class TeamGroupSubCommand {
       + TeamGroupSubCommand(service)
-      # registerDefaults(): void
     }
     TeamGroupSubCommand --|> SubCommand
 
@@ -28,7 +25,7 @@ package "fr.luc.crcore.command.builtin" {
       + {static} teamByName(service): ArgumentType<Team>
     }
 
-    ' === ADMIN commands (permission seule) ===
+    ' ─── ADMIN commands (permission seule, team par argument) ───
     package "admin" <<Rectangle>> {
       class TeamCreateSubCommand {
         perm: crcore.team.create
@@ -46,32 +43,30 @@ package "fr.luc.crcore.command.builtin" {
         perm: crcore.team.score
         args: <team> <name> <add|set> <value>
       }
-    }
-
-    ' === CHEF commands (permission + check chef) ===
-    package "chef" <<Rectangle>> {
       class TeamAddSubCommand {
         perm: crcore.team.add
-        args: <player>
+        args: <team> <player>
       }
       class TeamRemoveSubCommand {
         perm: crcore.team.remove
-        args: <player>
+        args: <team> <player>
       }
       class TeamTransferSubCommand {
         perm: crcore.team.transfer
-        args: <player>
+        args: <team> <player>
       }
       class TeamVisibilitySubCommand {
         perm: crcore.team.visibility
-        args: <vis>
+        args: <team> <vis>
       }
       class TeamSetSpawnSubCommand {
         perm: crcore.team.setspawn
+        args: <team>
+        playerOnly
       }
     }
 
-    ' === PLAYER commands ===
+    ' ─── PLAYER commands ───
     package "player" <<Rectangle>> {
       class TeamJoinSubCommand {
         perm: crcore.team.join
@@ -114,6 +109,11 @@ package "fr.luc.crcore.command.builtin" {
 }
 
 note bottom of TeamGroupSubCommand
+  Le rôle LEADER reste dans le modèle Team
+  (utilisable par les game plugins via l'API)
+  mais n'accorde aucun privilège de commande
+  dans le set par défaut.
+
   Override d'une feuille :
   core.getCoreCommand()
       .findSubCommand("team")