feat: /ia — chat question-and-answer backed by MiniMax

Adds an `ia` module: `/ia <pergunta>` sends the question to an
OpenAI-compatible chat-completions endpoint (MiniMax by default) and
posts the reply to chat.

Access is gated by `canalhandia.ia`, declared `default: op` so the
operator has it out of the box and LuckPerms can grant it to anyone
else.

The model can only ever produce chat text:

- the reply goes to sendMessage and nowhere else — it is never passed
  to the command dispatcher;
- no `tools`/`tool_choice` are sent, so there is nothing for the model
  to call;
- the system prompt states it has no server, shell or command access;
- replies are sanitised — colour codes stripped so they cannot forge
  server messages, newlines folded so one answer is one chat entry,
  and leading slashes removed so nothing reads as a command to run.

The API key is deliberately not a config value, since config.yml is
committed. It is read from MINIMAX_API_KEY or from
plugins/Canalhandia/minimax.key, which is now gitignored.

Cost is bounded by a per-player cooldown and a server-wide daily cap,
both visible in /canalhandia status. The HTTP call runs off the main
thread; only the delivery hops back onto it.

src/main/resources/plugin.yml

@@ -56,6 +56,10 @@ commands:
   f:
     description: Presta luto pela última morte.
     usage: /f
+  ia:
+    description: Faz uma pergunta simples para a IA.
+    usage: /ia <pergunta>
+    aliases: [pergunta]
 
 permissions:
   # Declared explicitly: an undeclared Bukkit permission falls back to op-only,
@@ -75,6 +79,9 @@ permissions:
   canalhandia.admin:
     description: Permite mudar módulos, modo, intervalo, categorias e reações.
     default: op
+  canalhandia.ia:
+    description: Permite usar /ia. Padrão op; o LuckPerms pode conceder a outros.
+    default: op
   canalhandia.isento:
     description: Quem tem isto nunca é sorteado como assunto.
     default: false